1
|
Guang J, Liu QP, Hopson R, Williard PG. Lithium pinacolone enolate solvated by hexamethylphosphoramide. J Am Chem Soc 2015; 137:7347-56. [PMID: 25933508 DOI: 10.1021/jacs.5b01906] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report the crystal structure of a substoichiometric, HMPA-trisolvated lithium pinacolone enolate tetramer (LiOPin)4·HMPA3 abbreviated as T3. In this tetramer one HMPA binds to lithium more strongly than the other two causing a reduction in spatial symmetry with corresponding loss of C3 symmetry. A variety of NMR experiments, including HMPA titration, diffusion coefficient-formula weight (D-FW) analysis, and other multinuclear one- and two-dimensional NMR techniques reveal that T3 is the major species in hydrocarbon solution when more than 0.6 equiv of HMPA is present. Due to a small amount of moisture from HMPA or air leaking into the solution, a minor complex was identified and confirmed by X-ray diffraction analysis as a mixed aggregate containing enolate, lithium hydroxide, and HMPA in a 4:2:4 ratio, [(LiOPin)4·(LiOH)2·HMPA4], that we refer to as pseudo-T4. A tetra-HMPA-solvated lithium cyclopentanone enolate tetramer was also prepared and characterized by X-ray diffraction, leading to the conclusion that steric effects dominate the formation and solvation of the pinacolone aggregates. An unusual mixed aggregate consisting of pinacolone enolate, lithium diisopropyl amide, lithium oxide, and HMPA in the ratio 5:1:1:2 is also described.
Collapse
Affiliation(s)
- Jie Guang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Qiyong Peter Liu
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Russell Hopson
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Paul G Williard
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| |
Collapse
|
2
|
Harrison-Marchand A, Mongin F. Mixed AggregAte (MAA): A Single Concept for All Dipolar Organometallic Aggregates. 1. Structural Data. Chem Rev 2013; 113:7470-562. [DOI: 10.1021/cr300295w] [Citation(s) in RCA: 145] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Anne Harrison-Marchand
- Laboratoire COBRA de l′Université de Rouen, INSA de Rouen, CNRS, UMR 6014 & FR 3038, IRCOF, Rue Tesnière, 76821 Mont St Aignan Cédex, France
| | - Florence Mongin
- Équipe Chimie et Photonique Moléculaires, Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS-Université de Rennes 1, Bâtiment 10A, case 1003, Avenue du Général Leclerc, 35042 Rennes Cédex, France
| |
Collapse
|
3
|
Tomasevich LL, Collum DB. Structure determination using the method of continuous variation: lithium phenolates solvated by protic and dipolar aprotic ligands. J Org Chem 2013; 78:7498-507. [PMID: 23806055 PMCID: PMC3759316 DOI: 10.1021/jo401080n] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The method of continuous variation (MCV) was used in conjunction with (6)Li NMR spectroscopy to characterize four lithium phenolates solvated by a range of solvents, including N,N,N',N'-tetramethylethylenediamine, Et2O, pyridine, protic amines, alcohols, and highly dipolar aprotic solvents. Dimers, trimers, and tetramers were observed, depending on the precise lithium phenolate-solvent combinations. Competition experiments (solvent swaps) provide insights into the relative propensities toward mixed solvation.
Collapse
Affiliation(s)
- Laura L. Tomasevich
- 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
| |
Collapse
|
4
|
De Vries TS, Bruneau AM, Liou LR, Subramanian H, Collum DB. Azaaldol condensation of a lithium enolate solvated by N,N,N',N'-tetramethylethylenediamine: dimer-based 1,2-addition to imines. J Am Chem Soc 2013; 135:4103-9. [PMID: 23413774 PMCID: PMC3715612 DOI: 10.1021/ja400345c] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The lithium enolate of tert-amylacetate solvated by N,N,N',N'-tetramethylethylenediamine (TMEDA) is shown to be a doubly chelated dimer. Adding the dimeric enolate to 4-fluorobenzaldehyde-N-phenylimine affords an N-lithiated β-amino ester shown to be monomeric using (6)Li and (15)N NMR spectroscopies. Rate studies using (19)F NMR spectroscopy reveal reaction orders consistent with a transition structure of stoichiometry [(ROLi)2(TMEDA)2(imine)](‡). Density functional theory computations explore several possible dimer-based transition structures with monodentate and bidentate coordination of TMEDA. Supporting rate studies using trans-N,N,N',N'-1,2-tetramethylcyclohexanediamine showing analogous rates and rate law suggest that TMEDA is fully chelated.
Collapse
Affiliation(s)
- Timothy S. De Vries
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| | - Angela M. Bruneau
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| | - Lara R. Liou
- 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
| |
Collapse
|
5
|
Suzuki M, Takashima-Hirano M, Koyama H, Yamaoka T, Sumi K, Nagata H, Hidaka H, Doi H. Efficient synthesis of [11C]H-1152, a PET probe specific for Rho-kinases, highly potential targets in diagnostic medicine and drug development. Tetrahedron 2012. [DOI: 10.1016/j.tet.2012.01.033] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
6
|
|
7
|
De Vries TS, Goswami A, Liou LR, Gruver JM, Jayne E, Collum DB. Lithium phenolates solvated by tetrahydrofuran and 1,2-dimethoxyethane: structure determination using the method of continuous variation. J Am Chem Soc 2009; 131:13142-54. [PMID: 19702308 PMCID: PMC2752606 DOI: 10.1021/ja9047784] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The method of continuous variation in conjunction with (6)Li NMR spectroscopy was used to characterize lithium phenolates solvated by tetrahydrofuran and 1,2-dimethoxyethane. The strategy relies on the formation of ensembles of homo- and heteroaggregated phenolates. The symmetries and concentration dependencies of the heteroaggregates attest to the aggregation numbers of the homoaggregates. The structurally diverse phenols afford substrate- and solvent-dependent combinations of lithium phenolate monomers, dimers, trimers, tetramers, and pentamers. We discuss the refinement of protocols for characterizing O-lithiated species. Computational studies examine further the substituent and solvent dependencies of aggregation.
Collapse
Affiliation(s)
- Timothy S De Vries
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA
| | | | | | | | | | | |
Collapse
|
8
|
Kolonko KJ, Biddle MM, Guzei IA, Reich HJ. Solution Structures of Lithium Enolates of Cyclopentanone, Cyclohexanone, Acetophenones, and Benzyl Ketones. Triple Ions and Higher Lithiate Complexes. J Am Chem Soc 2009; 131:11525-34. [DOI: 10.1021/ja903479p] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Margaret M. Biddle
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Ilia A. Guzei
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Hans J. Reich
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706
| |
Collapse
|
9
|
Johnson AL, Davidson MG, Pérez Y, Jones MD, Merle N, Raithby PR, Richards SP. Synthesis and structure of aluminium amine-phenolate complexes. Dalton Trans 2009:5551-8. [DOI: 10.1039/b904534a] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
10
|
|
11
|
Liou LR, McNeil AJ, Ramirez A, Toombes GES, Gruver JM, Collum DB. Lithium enolates of simple ketones: structure determination using the method of continuous variation. J Am Chem Soc 2008; 130:4859-68. [PMID: 18336025 PMCID: PMC2636850 DOI: 10.1021/ja7100642] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The method of continuous variation in conjunction with 6Li NMR spectroscopy was used to characterize lithium enolates derived from 1-indanone, cyclohexanone, and cyclopentanone in solution. The strategy relies on forming ensembles of homo- and heteroaggregated enolates. The enolates form exclusively chelated dimers in N,N,N',N'-tetramethylethylenediamine and cubic tetramers in tetrahydrofuran and 1,2-dimethoxyethane.
Collapse
Affiliation(s)
- Lara R Liou
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA
| | | | | | | | | | | |
Collapse
|