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Article: The stereochemistry of 2,4- and 2,3-disubstituted-γ-butyrolactones
Title | The stereochemistry of 2,4- and 2,3-disubstituted-γ-butyrolactones |
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Authors | |
Issue Date | 1975 |
Citation | Journal of the Chemical Society, Perkin Transactions 1, 1975, n. 15, p. 1480-1492 How to Cite? |
Abstract | Relative configurational assignments have been made to the 2,4-dimethyl- (7), 2,4-di-t-butyl- (8), 2,4-diphenyl-(9), 4-methyl-2-phenyl- (10), and 2-methyl-3-phenyl- (31) γ-butyrolactones on the basis of the stereoselective synthesis of their cis-isomers, from the corresponding disubstituted but-2-en-4-olides (2)-(5) and 2-methylene-3-phenyl-γ- butyrolactone (41) by hydrogenation over palladium. The characteristic features from the 1H n.m.r. spectra of the cis- and trans-isomers of (7)-(10) have been employed to assign relative configurations to the 2-methyl-4-phenyl- (11), 2,4-diethyl- (12), 2-ethyl-4-methyl- (13), and 2-butyl-4-methyl- (14) γ-butyrolactones. Equilibration studies on seven 2,4-disubstituted γ-butyrolactones [(7)-(10) and (12)-(14)] indicate that (i) the free energy differences between cis- and trans-isomers are small, and (ii) the cis- is thermodynamically more stable than the trans-isomer in all cases. The opposite situation is true of the 2-methyl-3-phenyl-γ-butyro-lactones (31) where the trans-isomet is found to predominate at equilibrium. 1H N.m.r. spectroscopic data suggest that the conformational behaviour of the five-membered ring in 2,4-disubstituted γ-butyrolactones is different for diastereoisomers but is not influenced to any great extent by the nature of the substituent groupings. |
Persistent Identifier | http://hdl.handle.net/10722/332822 |
ISSN | |
ISI Accession Number ID |
DC Field | Value | Language |
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dc.contributor.author | Hussain, S. A.M.Tayyeb | - |
dc.contributor.author | Ollis, W. David | - |
dc.contributor.author | Smith, Christopher | - |
dc.contributor.author | Stoddart, J. Fraser | - |
dc.date.accessioned | 2023-10-06T05:14:33Z | - |
dc.date.available | 2023-10-06T05:14:33Z | - |
dc.date.issued | 1975 | - |
dc.identifier.citation | Journal of the Chemical Society, Perkin Transactions 1, 1975, n. 15, p. 1480-1492 | - |
dc.identifier.issn | 1472-7781 | - |
dc.identifier.uri | http://hdl.handle.net/10722/332822 | - |
dc.description.abstract | Relative configurational assignments have been made to the 2,4-dimethyl- (7), 2,4-di-t-butyl- (8), 2,4-diphenyl-(9), 4-methyl-2-phenyl- (10), and 2-methyl-3-phenyl- (31) γ-butyrolactones on the basis of the stereoselective synthesis of their cis-isomers, from the corresponding disubstituted but-2-en-4-olides (2)-(5) and 2-methylene-3-phenyl-γ- butyrolactone (41) by hydrogenation over palladium. The characteristic features from the 1H n.m.r. spectra of the cis- and trans-isomers of (7)-(10) have been employed to assign relative configurations to the 2-methyl-4-phenyl- (11), 2,4-diethyl- (12), 2-ethyl-4-methyl- (13), and 2-butyl-4-methyl- (14) γ-butyrolactones. Equilibration studies on seven 2,4-disubstituted γ-butyrolactones [(7)-(10) and (12)-(14)] indicate that (i) the free energy differences between cis- and trans-isomers are small, and (ii) the cis- is thermodynamically more stable than the trans-isomer in all cases. The opposite situation is true of the 2-methyl-3-phenyl-γ-butyro-lactones (31) where the trans-isomet is found to predominate at equilibrium. 1H N.m.r. spectroscopic data suggest that the conformational behaviour of the five-membered ring in 2,4-disubstituted γ-butyrolactones is different for diastereoisomers but is not influenced to any great extent by the nature of the substituent groupings. | - |
dc.language | eng | - |
dc.relation.ispartof | Journal of the Chemical Society, Perkin Transactions 1 | - |
dc.title | The stereochemistry of 2,4- and 2,3-disubstituted-γ-butyrolactones | - |
dc.type | Article | - |
dc.description.nature | link_to_subscribed_fulltext | - |
dc.identifier.doi | 10.1039/p19750001480 | - |
dc.identifier.scopus | eid_2-s2.0-37049137658 | - |
dc.identifier.issue | 15 | - |
dc.identifier.spage | 1480 | - |
dc.identifier.epage | 1492 | - |
dc.identifier.isi | WOS:A1975AP70900010 | - |