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Malik M, Senatore R, Langer T, Holzer W, Pace V. Base-mediated homologative rearrangement of nitrogen-oxygen bonds of N-methyl- N-oxyamides. Chem Sci 2023; 14:10140-10146. [PMID: 37772102 PMCID: PMC10530184 DOI: 10.1039/d3sc03216g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Accepted: 08/26/2023] [Indexed: 09/30/2023] Open
Abstract
Due to the well known reactivity of C(O)-N functionalities towards canonical C1-homologating agents (e.g. carbenoids, diazomethane, ylides), resulting in the extrusion of the N-centered fragment en route to carbonyl compounds, formal C1-insertions within N-O bonds still remain obscure. Herein, we document the homologative transformation of N-methyl-N-oxyamides - with high tolerance for diverse O-substituents - into N-acyl-N,O-acetals. Under controlled basic conditions, the N-methyl group of the same starting materials acts as a competent precursor of the methylene synthon required for the homologation. The logic is levered on the formation of an electrophilic iminium ion (via N-O heterolysis) susceptible to nucleophilic attack by the alkoxide previously expulsed. The procedure documents genuine chemocontrol and flexibility, as judged by the diversity of substituents placed on both amide and nitrogen linchpins. The mechanistic rationale was validated through experiments conducted on D-labeled materials which unambiguously attributed the origin of the methylene fragment to the N-methyl group of the starting compounds.
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Affiliation(s)
- Monika Malik
- Department of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, University of Vienna Josef-Holaubek-Platz 2 1090 Vienna Austria
| | - Raffaele Senatore
- Department of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, University of Vienna Josef-Holaubek-Platz 2 1090 Vienna Austria
| | - Thierry Langer
- Department of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, University of Vienna Josef-Holaubek-Platz 2 1090 Vienna Austria
| | - Wolfgang Holzer
- Department of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, University of Vienna Josef-Holaubek-Platz 2 1090 Vienna Austria
| | - Vittorio Pace
- Department of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, University of Vienna Josef-Holaubek-Platz 2 1090 Vienna Austria
- Department of Chemistry, University of Turin Via Giuria 7 10125 Turin Italy
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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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Turlik A, Ando K, Mackey P, Alcock E, Light M, McGlacken GP, Houk KN. Mechanism and Origins of Stereoselectivity of the Aldol-Tishchenko Reaction of Sulfinimines. J Org Chem 2021; 86:4296-4303. [PMID: 33586983 PMCID: PMC8279497 DOI: 10.1021/acs.joc.0c02862] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Density functional theory computations
have elucidated the mechanism
and origins of stereoselectivity in McGlacken’s aldol-Tishchenko
reaction for the diastereoselective synthesis of 1,3-amino alcohols
using Ellman’s t-butylsulfinimines as chiral
auxiliaries. Variations of stereochemical outcome are dependent on
the nature of the ketone starting materials used, and the aspects
leading to these differences have been rationalized. The intramolecular
hydride transfer step is the rate- and stereochemistry-determining
step, and all prior steps are reversible.
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Affiliation(s)
- Aneta Turlik
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, United States
| | - Kaori Ando
- Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, Yanagido 1-1, Gifu 501-1193, Japan
| | - Pamela Mackey
- School of Chemistry and Analytical and Biological Chemistry Research Facility, University College Cork, Cork, Ireland
| | - Emma Alcock
- School of Chemistry and Analytical and Biological Chemistry Research Facility, University College Cork, Cork, Ireland
| | - Mark Light
- School of Chemistry, University of Southampton, Southampton, SO17 1BJ, United Kingdom
| | - Gerard P McGlacken
- School of Chemistry and Analytical and Biological Chemistry Research Facility, University College Cork, Cork, Ireland
| | - K N Houk
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, United States
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4
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Pluta R, Li Z, Kumagai N, Shibasaki M. Z-Enolate Geometry in the Thioamide Aldol Reaction Illuminated by the 7-Azaindoline Auxiliary. Org Lett 2020; 22:791-794. [PMID: 31829612 DOI: 10.1021/acs.orglett.9b04120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Z or E enolate geometry is the primary determinant of diastereoselectivity in the aldol reaction. Although amide and thioamide enolates are anticipated to have predominantly the E geometry because of the intrinsic steric demand, spectroscopic confirmation of the geometry in solution has remained elusive, particularly in the realm of highly stereoselective catalytic asymmetric aldol reactions. Herein we demonstrate that the 7-azaindoline auxiliary enables direct observation of the exclusive formation of the Z-enolate of the thioamide en route to a highly syn-selective aldol reaction.
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Affiliation(s)
- Roman Pluta
- Institute of Microbial Chemistry , 3-14-23 Kamiosaki , Shinagawa-ku , Tokyo 141-0021 , Japan
| | - Zhao Li
- Institute of Microbial Chemistry , 3-14-23 Kamiosaki , Shinagawa-ku , Tokyo 141-0021 , Japan
| | - Naoya Kumagai
- Institute of Microbial Chemistry , 3-14-23 Kamiosaki , Shinagawa-ku , Tokyo 141-0021 , Japan
| | - Masakatsu Shibasaki
- Institute of Microbial Chemistry , 3-14-23 Kamiosaki , Shinagawa-ku , Tokyo 141-0021 , Japan
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5
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Pasturaud K, Rkein B, Sanselme M, Sebban M, Lakhdar S, Durandetti M, Legros J, Chataigner I. The facile dearomatization of nitroaromatic compounds using lithium enolates of unsaturated ketones in conjugate additions and (4+2) formal cycloadditions. Chem Commun (Camb) 2019; 55:7494-7497. [PMID: 31185071 DOI: 10.1039/c9cc02924a] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The dearomatization of conventional nitroarenes by lithiated enolates derived from methyl vinyl ketones easily takes place, following a formal (4+2) cycloaddition process. While nitroindoles react readily with in situ generated conjugated enolates, the deaggregation of these latter species using HMPA extends the reaction scope to the more aromatic nitronaphthalenes and pyridines.
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Affiliation(s)
- Karine Pasturaud
- Normandie Univ., UNIROUEN, INSA Rouen, CNRS, COBRA, 76000 Rouen, France.
| | - Batoul Rkein
- Normandie Univ., UNIROUEN, INSA Rouen, CNRS, COBRA, 76000 Rouen, France.
| | | | - Muriel Sebban
- Normandie Univ., UNIROUEN, INSA Rouen, CNRS, COBRA, 76000 Rouen, France.
| | - Sami Lakhdar
- Normandie Univ., LCMT, ENSICAEN, UNICAEN, CNRS, 6, Boulevard Maréchal Juin, Caen 14000, France
| | - Muriel Durandetti
- Normandie Univ., UNIROUEN, INSA Rouen, CNRS, COBRA, 76000 Rouen, France.
| | - Julien Legros
- Normandie Univ., UNIROUEN, INSA Rouen, CNRS, COBRA, 76000 Rouen, France.
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6
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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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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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