1
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Wang Z, Debuigne A. Radical Polymerization of Methylene Heterocyclic Compounds: Functional Polymer Synthesis and Applications. POLYM REV 2023. [DOI: 10.1080/15583724.2023.2181819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Affiliation(s)
- Zhuoqun Wang
- Center for Education and Research on Macromolecules (CERM), CESAM Research Unit, Chemistry Department, University of Liege, Liege, Belgium
| | - Antoine Debuigne
- Center for Education and Research on Macromolecules (CERM), CESAM Research Unit, Chemistry Department, University of Liege, Liege, Belgium
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2
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Lui NM, MacMillan SN, Collum DB. Lithiated Oppolzer Enolates: Solution Structures, Mechanism of Alkylation, and Origin of Stereoselectivity. J Am Chem Soc 2022; 144:23379-23395. [PMID: 36534055 PMCID: PMC10071589 DOI: 10.1021/jacs.2c09341] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Camphorsultam-based lithium enolates referred to colloquially as Oppolzer enolates are examined spectroscopically, crystallographically, kinetically, and computationally to ascertain the mechanism of alkylation and the origin of the stereoselectivity. Solvent- and substrate-dependent structures include tetramers for alkyl-substituted enolates in toluene, unsymmetric dimers for aryl-substituted enolates in toluene, substrate-independent symmetric dimers in THF and THF/toluene mixtures, HMPA-bridged trisolvated dimers at low HMPA concentrations, and disolvated monomers for the aryl-substituted enolates at elevated HMPA concentrations. Extensive analyses of the stereochemistry of aggregation are included. Rate studies for reaction with allyl bromide implicate an HMPA-solvated ion pair with a +Li(HMPA)4 counterion. Dependencies on toluene and THF are attributed to exclusively secondary-shell (medium) effects. Aided by density functional theory (DFT) computations, a stereochemical model is presented in which neither chelates nor the lithium gegenion serves roles. The stereoselectivity stems from the chirality within the sultam ring and not the camphor skeletal core.
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Affiliation(s)
- Nathan M Lui
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University Ithaca, New York 14853-1301, United States
| | - Samantha N MacMillan
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University Ithaca, New York 14853-1301, United States
| | - David B Collum
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University Ithaca, New York 14853-1301, United States
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3
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Unusual (3 THF)-microsolvated dimers and donor-free aggregates of two lithium enolates. Tetrahedron 2021. [DOI: 10.1016/j.tet.2021.132500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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4
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Woltornist RA, Collum DB. Ketone Enolization with Sodium Hexamethyldisilazide: Solvent- and Substrate-Dependent E- Z Selectivity and Affiliated Mechanisms. J Am Chem Soc 2021; 143:17452-17464. [PMID: 34643382 PMCID: PMC10042305 DOI: 10.1021/jacs.1c06529] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Ketone enolization by sodium hexamethyldisilazide (NaHMDS) shows a marked solvent and substrate dependence. Enolization of 2-methyl-3-pentanone reveals E-Z selectivities in Et3N/toluene (20:1), methyl-t-butyl ether (MTBE, 10:1), N,N,N',N″,N″-pentamethyldiethylenetriamine (PMDTA)/toluene (8:1), TMEDA/toluene (4:1), diglyme (1:1), DME (1:22), and tetrahydrofuran (THF) (1:90). Control experiments show slow or nonexistent stereochemical equilibration in all solvents except THF. Enolate trapping with Me3SiCl/Et3N requires warming to -40 °C whereas Me3SiOTf reacts within seconds. In situ enolate trapping at -78 °C using preformed NaHMDS/Me3SiCl mixtures is effective in Et3N/toluene yet fails in THF by forming (Me3Si)3N. Rate studies show enolization via mono- and disolvated dimers in Et3N/toluene, disolvated dimers in TMEDA, trisolvated monomers in THF/toluene, and free ions with PMDTA. Density functional theory computations explore the selectivities via the E- and Z-based transition structures. Failures of theory-experiment correlations of ionic fragments were considerable even when isodesmic comparisons could have canceled electron correlation errors. Swapping 2-methyl-3-pentanone with a close isostere, 2-methylcyclohexanone, causes a fundamental change in the mechanism to a trisolvated-monomer-based enolization in THF.
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Affiliation(s)
- Ryan A Woltornist
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States
| | - David B Collum
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States
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5
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Gu ZY, Xia JB. [3 + 1 + 1] cyclization of vinyl oxiranes with azides and CO by tandem palladium catalysis: efficient synthesis of oxazolidinones. Org Chem Front 2021. [DOI: 10.1039/d1qo00591j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
An efficient [3 + 1 + 1] cyclization of vinyl oxiranes for the synthesis of oxazolidinones has been developed via tandem palladium catalysis.
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Affiliation(s)
- Zheng-Yang Gu
- College of Textiles and Clothing & Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province
- Yancheng Institute of Technology
- Jiangsu
- China
- State Key Laboratory for Oxo Synthesis and Selective Oxidation
| | - Ji-Bao Xia
- State Key Laboratory for Oxo Synthesis and Selective Oxidation
- Center for Excellence in Molecular Synthesis
- Suzhou Research Institute of LICP
- Lanzhou Institute of Chemical Physics (LICP)
- University of Chinese Academy of Sciences
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6
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Wang Z, Detrembleur C, Debuigne A. Reversible deactivation radical (co)polymerization of dimethyl methylene oxazolidinone towards responsive vicinal aminoalcohol-containing copolymers. Polym Chem 2020. [DOI: 10.1039/d0py01255f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Well-defined oxazolidinone-containing copolymers produced by controlled radical polymerization give access to multi-responsive vicinal amino-alcohol functional poly(vinyl alcohol)s.
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Affiliation(s)
- Zhuoqun Wang
- Center for Education and Research on Macromolecules (CERM)
- CESAM Research Unit
- University of Liege
- 4000 Liege
- Belgium
| | - Christophe Detrembleur
- Center for Education and Research on Macromolecules (CERM)
- CESAM Research Unit
- University of Liege
- 4000 Liege
- Belgium
| | - Antoine Debuigne
- Center for Education and Research on Macromolecules (CERM)
- CESAM Research Unit
- University of Liege
- 4000 Liege
- Belgium
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7
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Diaz-Muñoz G, Miranda IL, Sartori SK, de Rezende DC, Alves Nogueira Diaz M. Use of chiral auxiliaries in the asymmetric synthesis of biologically active compounds: A review. Chirality 2019; 31:776-812. [PMID: 31418934 DOI: 10.1002/chir.23103] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 05/13/2019] [Accepted: 05/22/2019] [Indexed: 01/16/2023]
Abstract
This review article describes the use of some of the most popular chiral auxiliaries in the asymmetric synthesis of biologically active compounds. Chiral auxiliaries derived from naturally occurring compounds, such as amino acids, carbohydrates, and terpenes, are considered essential tools for the construction of highly complex molecules. We highlight the auxiliaries of Evans, Corey, Yamada, Enders, Oppolzer, and Kunz, which led to remarkable progress in asymmetric synthesis in the last decades and continue to bring advances until the present day.
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Affiliation(s)
- Gaspar Diaz-Muñoz
- Department of Chemistry, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Izabel Luzia Miranda
- Department of Chemistry, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Suélen Karine Sartori
- Department of Chemistry, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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8
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Cao Z, Xu P, Luo Q, Li X, Yu D, Fang H, Shi Z. Conversion of Carbonyl Compounds to Olefins
via
Enolate Intermediate. CHINESE J CHEM 2019. [DOI: 10.1002/cjoc.201800554] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Zhi‐Chao Cao
- Department of ChemistryFudan University Shanghai 200433 China
- College of Chemistry and Molecular EngineeringPeking University Beijing 100871 China
| | - Pei‐Lin Xu
- College of Chemistry and Molecular EngineeringPeking University Beijing 100871 China
| | - Qin‐Yu Luo
- College of Chemistry and Molecular EngineeringPeking University Beijing 100871 China
| | - Xiao‐Lei Li
- College of Chemistry and Molecular EngineeringPeking University Beijing 100871 China
| | - Da‐Gang Yu
- College of ChemistrySichuan University Chengdu Sichuan 610064 China
| | - Huayi Fang
- Department of ChemistryFudan University Shanghai 200433 China
| | - Zhang‐Jie Shi
- Department of ChemistryFudan University Shanghai 200433 China
- College of Chemistry and Molecular EngineeringPeking University Beijing 100871 China
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9
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Zhang Z, Collum DB. Structures and Reactivities of Sodiated Evans Enolates: Role of Solvation and Mixed Aggregation on the Stereochemistry and Mechanism of Alkylations. J Am Chem Soc 2019; 141:388-401. [PMID: 30462500 PMCID: PMC7185956 DOI: 10.1021/jacs.8b10364] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Oxazolidinone-based sodiated enolates (Evans enolates) were generated using sodium diisopropylamide (NaDA) or sodium hexamethyldisilazide (NaHMDS) in the presence of N,N,N',N'-tetramethylethylenediamine (TMEDA), ( R,R)- trans- N,N,N',N'-tetramethylcyclohexanediamine [( R,R)-TMCDA], or ( S,S)-TMCDA. 13C NMR spectroscopic analysis in conjunction with the method of continuous variations (MCV), x-ray crystallography, and density functional theory (DFT) computations revealed the enolates to be octahedral bis-diamine-chelated monomers. Rate and computational studies of an alkylation with allyl bromide implicate a bis-diamine-chelated-monomer-based transition structure. The sodiated Evans enolates form mixed dimers with NaHMDS, NaDA, or sodium 2,6-di- tert-butylphenolate, the reactivities of which are examined. Stereoselective quaternizations, aldol additions, and azaaldol additions are described.
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Affiliation(s)
- Zirong Zhang
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| | - David B. Collum
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
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10
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Barát V, Csókás D, Bates RW. Synthesis of (−)-Cytisine Using a 6-endo aza-Michael Addition. J Org Chem 2018; 83:9088-9095. [DOI: 10.1021/acs.joc.8b01156] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Viktor Barát
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University 637371, Singapore
| | - Dániel Csókás
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University 637371, Singapore
| | - Roderick W. Bates
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University 637371, Singapore
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11
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Jermaks J, Tallmadge EH, Keresztes I, Collum DB. Lithium Amino Alkoxide-Evans Enolate Mixed Aggregates: Aldol Addition with Matched and Mismatched Stereocontrol. J Am Chem Soc 2018; 140:3077-3090. [PMID: 29457718 PMCID: PMC6059615 DOI: 10.1021/jacs.7b13776] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Building on structural and mechanistic studies of lithiated enolates derived from acylated oxazolidinones (Evans enolates) and chiral lithiated amino alkoxides, we found that amino alkoxides amplify the enantioselectivity of aldol additions. The pairing of enantiomeric series affords matched and mismatched stereoselectivities. The structures of mixed tetramers showing 2:2 and 3:1 (alkoxide-rich) stoichiometries are determined spectroscopically. Rate and computational studies provide a viable mechanistic and stereochemical model based on the direct reaction of the 3:1 mixed tetramers, but they raise unanswered questions for the 2:2 mixed aggregates.
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Affiliation(s)
- Janis Jermaks
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Evan H. Tallmadge
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Ivan Keresztes
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - David B. Collum
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
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12
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Ma W, Liang X, Ye W, Wang Y, Min L, He S, Lee CS. Total Syntheses of Basiliolide A1
, Basiliolide A2
, Basiliolide C, and their Structural Analogues. European J Org Chem 2018. [DOI: 10.1002/ejoc.201701211] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Wenjing Ma
- Laboratory of Chemical Genomics; Peking University Shenzhen Graduate School; Lishui Road 518055 Shenzhen China
| | - Xuefeng Liang
- Laboratory of Chemical Genomics; Peking University Shenzhen Graduate School; Lishui Road 518055 Shenzhen China
| | - Wejian Ye
- Laboratory of Chemical Genomics; Peking University Shenzhen Graduate School; Lishui Road 518055 Shenzhen China
| | - Yuena Wang
- Laboratory of Chemical Genomics; Peking University Shenzhen Graduate School; Lishui Road 518055 Shenzhen China
| | - Long Min
- Laboratory of Chemical Genomics; Peking University Shenzhen Graduate School; Lishui Road 518055 Shenzhen China
| | - Shuzhong He
- School of Pharmaceutical Sciences; Guizhou University; 550025 Guiyang Guizhou China
| | - Chi-Sing Lee
- Laboratory of Chemical Genomics; Peking University Shenzhen Graduate School; Lishui Road 518055 Shenzhen China
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13
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Heras C, Gómez-Palomino A, Romea P, Urpí F, Bofill JM, Moreira IDPR. Experimental and Computational Evidence of the Biradical Structure and Reactivity of Titanium(IV) Enolates. J Org Chem 2017; 82:8909-8916. [PMID: 28783338 DOI: 10.1021/acs.joc.7b01174] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Quantum chemical calculations have unveiled the unexpected biradical character of titanium(IV) enolates from N-acyl oxazolidinones and thiazolidinethiones. The electronic structure of these species therefore involves a valence tautomerism consisting of an equilibrium between a closed shell (formally Ti(IV) enolates) and an open shell, biradical, singlet (formally Ti(III) enolates) electronic states, whose origin is to be basically found in changes of the Ti-O distance. Spectroscopic studies of the intermediate species lend support to such a model, which also turns out to be crucial for a better understanding of the overall reactivity of titanium(IV) enolates. In this context, a thorough computational analysis of the radical addition of titanium(IV) enolates from N-acyl oxazolidinones to TEMPO has permitted us to suggest an entire mechanism, which accounts for the experimental details and the diastereoselectivity of the process. All together, this evidence highlights the relevance of biradical intermediates from titanium(IV) enolates and may be a useful contribution to the foundations of a more insightful comprehension of the structure and reactivity of titanium(IV) enolates.
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Affiliation(s)
- Carlos Heras
- Departament de Química Inorgànica i Orgànica, Secció de Química Orgànica. Universitat de Barcelona , Carrer Martí i Franquès 1-11, 08028 Barcelona, Catalonia, Spain
| | - Alejandro Gómez-Palomino
- Departament de Química Inorgànica i Orgànica, Secció de Química Orgànica. Universitat de Barcelona , Carrer Martí i Franquès 1-11, 08028 Barcelona, Catalonia, Spain.,Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona , Avinguda Diagonal 645, 08028 Barcelona, Catalonia, Spain
| | - Pedro Romea
- Departament de Química Inorgànica i Orgànica, Secció de Química Orgànica. Universitat de Barcelona , Carrer Martí i Franquès 1-11, 08028 Barcelona, Catalonia, Spain.,Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona , Avinguda Diagonal 645, 08028 Barcelona, Catalonia, Spain
| | - Fèlix Urpí
- Departament de Química Inorgànica i Orgànica, Secció de Química Orgànica. Universitat de Barcelona , Carrer Martí i Franquès 1-11, 08028 Barcelona, Catalonia, Spain.,Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona , Avinguda Diagonal 645, 08028 Barcelona, Catalonia, Spain
| | - Josep Maria Bofill
- Departament de Química Inorgànica i Orgànica, Secció de Química Orgànica. Universitat de Barcelona , Carrer Martí i Franquès 1-11, 08028 Barcelona, Catalonia, Spain.,Institut de Química Teòrica i Computacional de la Universitat de Barcelona (IQTCUB), Universitat de Barcelona , Carrer Martı́ i Franquès 1-11, 08028 Barcelona, Catalonia, Spain
| | - Ibério de P R Moreira
- Institut de Química Teòrica i Computacional de la Universitat de Barcelona (IQTCUB), Universitat de Barcelona , Carrer Martı́ i Franquès 1-11, 08028 Barcelona, Catalonia, Spain.,Departament de Ciència dels Materials i Química Física, Secció de Química Física, Universitat de Barcelona , Carrer Martí i Franquès 1-11, 08028 Barcelona, Catalonia, Spain
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14
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Barozzino-Consiglio G, Hamdoun G, Fressigné C, Harrison-Marchand A, Maddaluno J, Oulyadi H. A Combined 1
H/6
Li NMR DOSY Strategy Finally Uncovers the Structure of Isopropyllithium in THF. Chemistry 2017; 23:12475-12479. [DOI: 10.1002/chem.201702990] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Indexed: 11/09/2022]
Affiliation(s)
| | - Ghanem Hamdoun
- Normandie Université, UNIROUEN, INSA de Rouen, CNRS; Laboratoire COBRA (UMR 6014 & FR 3038); 76000 Rouen France
| | - Catherine Fressigné
- Normandie Université, UNIROUEN, INSA de Rouen, CNRS; Laboratoire COBRA (UMR 6014 & FR 3038); 76000 Rouen France
| | - Anne Harrison-Marchand
- Normandie Université, UNIROUEN, INSA de Rouen, CNRS; Laboratoire COBRA (UMR 6014 & FR 3038); 76000 Rouen France
| | - Jacques Maddaluno
- Normandie Université, UNIROUEN, INSA de Rouen, CNRS; Laboratoire COBRA (UMR 6014 & FR 3038); 76000 Rouen France
| | - Hassan Oulyadi
- Normandie Université, UNIROUEN, INSA de Rouen, CNRS; Laboratoire COBRA (UMR 6014 & FR 3038); 76000 Rouen France
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15
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Zhang Z, Collum DB. Evans Enolates: Structures and Mechanisms Underlying the Aldol Addition of Oxazolidinone-Derived Boron Enolates. J Org Chem 2017; 82:7595-7601. [PMID: 28686020 DOI: 10.1021/acs.joc.7b01365] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The soft enolization of an acylated oxazolidinone using di-n-butylboron triflate (n-Bu2BOTf) and trialkylamines and subsequent aldol addition was probed structurally and mechanistically using a combination of IR and NMR spectroscopies. None of the species along the reaction coordinate show a penchant for aggregating. Complexation of the acylated oxazolidinone by n-Bu2BOTf was too rapid to monitor, as was the subsequent enolization with Et3N (triethylamine). The preformed n-Bu2BOTf·Et3N complex, displaying muted Lewis acidity and affiliated tractable rates, reveals a rate-limiting complexation via a transition structure with a complicated counterion. n-Bu2BOTf·i-Bu3N bearing a hindered amine shifts the rate-limiting step to proton transfer. Rate studies show that the aldol addition with isobutyraldehyde occurs as proffered by others.
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Affiliation(s)
- Zirong Zhang
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University , Ithaca, New York 14853-1301, United States
| | - David B Collum
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University , Ithaca, New York 14853-1301, United States
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16
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Cano R, Zakarian A, McGlacken GP. Direct Asymmetric Alkylation of Ketones: Still Unconquered. Angew Chem Int Ed Engl 2017; 56:9278-9290. [PMID: 28497890 DOI: 10.1002/anie.201703079] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 04/27/2017] [Indexed: 01/07/2023]
Abstract
The alkylation of ketones is taught at basic undergraduate level. In many cases this transformation leads to the formation of a new stereogenic center. However, the apparent simplicity of the transformation is belied by a number of problems. So much so, that a general method for the direct asymmetric alkylation of ketones remains an unmet target. Despite the advancement of organocatalysis and transition-metal catalysis, neither field has provided an adequate solution. Indeed, even use of an efficient and general stoichiometric chiral reagent has yet to be reported. Herein we describe the state-of-the-art in terms of direct alkylation reactions of some carbonyl groups. We outline the limited progress that has been made with ketones, and potential routes towards ultimately achieving a widely applicable methodology for the asymmetric alkylation of ketones.
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Affiliation(s)
- Rafael Cano
- Department of Chemistry, University College Cork, Cork, Ireland.,Analytical and Biological Chemistry Research Facility, University College Cork, Cork, Ireland
| | - Armen Zakarian
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, 93106, USA
| | - Gerard P McGlacken
- Department of Chemistry, University College Cork, Cork, Ireland.,Analytical and Biological Chemistry Research Facility, University College Cork, Cork, Ireland
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17
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Cano R, Zakarian A, McGlacken GP. Direkte asymmetrische Alkylierung von Ketonen: noch immer ein unerreichtes Ziel. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201703079] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Rafael Cano
- Department of Chemistry; University College Cork; Cork Irland
- Analytical and Biological Chemistry Research Facility; University College Cork; Cork Irland
| | - Armen Zakarian
- Department of Chemistry and Biochemistry; University of California; Santa Barbara CA 93106 USA
| | - Gerard P. McGlacken
- Department of Chemistry; University College Cork; Cork Irland
- Analytical and Biological Chemistry Research Facility; University College Cork; Cork Irland
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18
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Liang X, Zhou L, Min L, Ye W, Bao W, Ma W, Yang Q, Qiao F, Zhang X, Lee CS. Diastereoselective Total Synthesis of (±)-Basiliolide B and (±)-epi-8-Basiliolide B. J Org Chem 2017; 82:3463-3481. [DOI: 10.1021/acs.joc.6b02921] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xuefeng Liang
- Laboratory of Chemical Genomics,
School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen University Town, Xili, Shenzhen 518055, China
| | - Liyan Zhou
- Laboratory of Chemical Genomics,
School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen University Town, Xili, Shenzhen 518055, China
| | - Long Min
- Laboratory of Chemical Genomics,
School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen University Town, Xili, Shenzhen 518055, China
| | - Weijian Ye
- Laboratory of Chemical Genomics,
School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen University Town, Xili, Shenzhen 518055, China
| | - Wenli Bao
- Laboratory of Chemical Genomics,
School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen University Town, Xili, Shenzhen 518055, China
| | - Wenjing Ma
- Laboratory of Chemical Genomics,
School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen University Town, Xili, Shenzhen 518055, China
| | - Qianqian Yang
- Laboratory of Chemical Genomics,
School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen University Town, Xili, Shenzhen 518055, China
| | - Fangfang Qiao
- Laboratory of Chemical Genomics,
School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen University Town, Xili, Shenzhen 518055, China
| | - Xinhao Zhang
- Laboratory of Chemical Genomics,
School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen University Town, Xili, Shenzhen 518055, China
| | - Chi-Sing Lee
- Laboratory of Chemical Genomics,
School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen University Town, Xili, Shenzhen 518055, China
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19
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Houghton MJ, Collum DB. Lithium Enolates Derived from Weinreb Amides: Insights into Five-Membered Chelate Rings. J Org Chem 2016; 81:11057-11064. [PMID: 27749060 PMCID: PMC5261255 DOI: 10.1021/acs.joc.6b02067] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Enolization of O-methyl hydroxamic acids (Weinreb amides) in tetrahydrofuran solution with lithium diisopropylamide affords predominantly tetrameric enolates. Aryl substituents on the enolates promote deaggregation. The aggregation states are assigned by using the method of continuous variation in conjunction with 6Li NMR spectroscopy. Decoalescence of the tetramer resonance below -100 °C shows considerable spectral complexity attributed to isomerism of the methoxy-based chelates. Density functional theory calculations were used to examine the consequences of the bite angle of five-membered chelates in cubic tetramers and resulting solvation numbers that were higher than anticipated.
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Affiliation(s)
- Michael J. Houghton
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - David B. Collum
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
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20
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Houghton MJ, Huck CJ, Wright SW, Collum DB. Lithium Enolates Derived from Pyroglutaminol: Mechanism and Stereoselectivity of an Azaaldol Addition. J Am Chem Soc 2016; 138:10276-83. [PMID: 27500546 PMCID: PMC5240537 DOI: 10.1021/jacs.6b05481] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A lithium enolate derived from an acetonide-protected pyroglutaminol undergoes a highly selective azaaldol addition with (E)-N-phenyl-1-[2-(trifluoromethyl)phenyl]methanimine. The selectivity is sensitive to tetrahydrofuran (THF) concentration, temperature, and the presence of excess lithium diisopropylamide base. Rate studies show that the observable tetrasolvated dimeric enolate undergoes reversible deaggregation, with the reaction proceeding via a disolvated-monomer-based transition structure. Limited stereochemical erosion stems from the intervention of a trisolvated-monomer-based pathway, which is suppressed at low THF concentrations and elevated temperature. Endofacial selectivity observed with excess lithium diisopropylamide (LDA) is traced to an intermediate dianion formed by subsequent lithiation of the monomeric azaaldol adduct, which is characterized as both a dilithio form and a trilithio dianion-LDA mixed aggregate.
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Affiliation(s)
- Michael J. Houghton
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University Ithaca, New York 14853–1301
| | - Christopher J. Huck
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University Ithaca, New York 14853–1301
| | - Stephen W. Wright
- Worldwide Medicinal Chemistry, Pfizer Global Research and Development, 445 Eastern Point Road, Groton, CT 06340
| | - David B. Collum
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University Ithaca, New York 14853–1301
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21
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Ma Y, Mack KA, Liang J, Keresztes I, Collum DB, Zakarian A. Mixed Aggregates of the Dilithiated Koga Tetraamine: NMR Spectroscopic and Computational Studies. Angew Chem Int Ed Engl 2016; 55:10093-7. [PMID: 27435147 DOI: 10.1002/anie.201605199] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Indexed: 01/11/2023]
Abstract
A combination of (1) H, (6) Li, (13) C, and (15) N NMR spectroscopies and density functional theory computations explores the formation of mixed aggregates by a dilithium salt of a C2 -symmetric chiral tetraamine (Koga's base). Lithium halides, acetylides, alkoxides, and monoalkylamides form isostructural trilithiated mixed aggregates with few exceptions. (6) Li-(13) C and (6) Li-(15) N couplings reveal heretofore undetected transannular contacts (laddering) with lithium acetylides and lithium monoalkylamides. Marked temperature-dependent (15) N chemical shifts seem to be associated with this laddering. Computational studies shed light on the general structures of the aggregates, their penchant for laddering, and the stereochemical consequences of aggregation.
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Affiliation(s)
- Yun Ma
- Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853-1301, USA
| | - Kyle A Mack
- Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853-1301, USA
| | - Jun Liang
- Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853-1301, USA
| | - Ivan Keresztes
- Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853-1301, USA
| | - David B Collum
- Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853-1301, USA.
| | - Armen Zakarian
- Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA.
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Ma Y, Mack KA, Liang J, Keresztes I, Collum DB, Zakarian A. Mixed Aggregates of the Dilithiated Koga Tetraamine: NMR Spectroscopic and Computational Studies. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201605199] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Yun Ma
- Chemistry and Chemical Biology; Cornell University; Ithaca NY 14853-1301 USA
| | - Kyle A. Mack
- Chemistry and Chemical Biology; Cornell University; Ithaca NY 14853-1301 USA
| | - Jun Liang
- Chemistry and Chemical Biology; Cornell University; Ithaca NY 14853-1301 USA
| | - Ivan Keresztes
- Chemistry and Chemical Biology; Cornell University; Ithaca NY 14853-1301 USA
| | - David B. Collum
- Chemistry and Chemical Biology; Cornell University; Ithaca NY 14853-1301 USA
| | - Armen Zakarian
- Chemistry and Biochemistry; University of California, Santa Barbara; Santa Barbara CA 93106 USA
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Houghton MJ, Biok NA, Huck CJ, Algera RF, Keresztes I, Wright SW, Collum DB. Lithium Enolates Derived from Pyroglutaminol: Aggregation, Solvation, and Atropisomerism. J Org Chem 2016; 81:4149-57. [PMID: 27035057 PMCID: PMC5245164 DOI: 10.1021/acs.joc.6b00459] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Lithium enolates derived from protected pyroglutaminols were characterized by using (6)Li, (13)C, and (19)F NMR spectroscopies in conjunction with the method of continuous variations. Mixtures of tetrasolvated dimers and tetrasolvated tetramers in different proportions depend on the steric demands of the hemiaminal protecting group, tetrahydrofuran concentration, and the presence or absence of an α-fluoro moiety. The high steric demands of the substituted bicyclo[3.3.0] ring system promote dimers to an unusual extent and allow solvents and atropisomers in cubic tetramers to be observed in the slow-exchange limit. Pyridine used as a (6)Li chemical shift reagent proved useful in assigning solvation numbers.
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Affiliation(s)
- Michael J. Houghton
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| | - Naomi A. Biok
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| | - Christopher J. Huck
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| | - Russell F. Algera
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| | - Ivan Keresztes
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| | - Stephen W. Wright
- Worldwide Medicinal Chemistry, Pfizer Global Research and Development, 445 Eastern Point Road, Groton, CT 06340
| | - David B. Collum
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
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Tallmadge EH, Jermaks J, Collum DB. Structure-Reactivity Relationships in Lithiated Evans Enolates: Influence of Aggregation and Solvation on the Stereochemistry and Mechanism of Aldol Additions. J Am Chem Soc 2016; 138:345-55. [PMID: 26639525 PMCID: PMC4762877 DOI: 10.1021/jacs.5b10980] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Aldol additions to isobutyraldehyde and cyclohexanone with lithium enolates derived from acylated oxazolidinones (Evans enolates) are described. Previously characterized trisolvated dimeric enolates undergo rapid addition to isobutyraldehyde to give a 12:1 syn:syn selectivity in high yield along with small amounts of one anti isomer. The efficacy of the addition depends critically on aging effects and the reaction quench. Unsolvated tetrameric enolates that form on warming the solutions are unreactive toward isobutyraldehyde and undergo retroaldol reaction under forcing conditions. Additions to cyclohexanone are relatively slow but form a single isomeric adduct in >80% yield. The ketone-derived aldolates are robust. All attempts to control stereoselectivity by controlling aggregation failed. Rate studies of addition to cyclohexanone trace the lack of aggregation-dependent selectivities to a monomer-based mechanism. The synthetic implications and possible utility of lithium enolates in Evans aldol additions are discussed.
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Affiliation(s)
- Evan H. Tallmadge
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Janis Jermaks
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - David B. Collum
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
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