98043-33-5Relevant academic research and scientific papers
Enantioselective enolate protonation with chiral anilines: Scope, structural requirements, and mechanistic implications
Vedejs,Kruger,Lee,Sakata,Stec,Suna
, p. 4602 - 4607 (2007/10/03)
High enantioselectivity has been demonstrated in the protonation of N,N- diisopropyl amides (Table, 1, entries 1-4, 7, and 10-13) derived from certain β,γ unsaturated acids. Depending on double bond geometry and the degree of substitution at the γ-carbon, γ-protonation can be a competing reaction in the case of the aliphatic substrates 12, 14b, 14d, and 18. The evidence is most consistent with a mechanism that involves proton transfer from 1a to a mixed aggregate consisting of enolate 4a and the lithiated amide 5, but direct proton transfer from 1a to the enolate is not ruled out.
STEREOCHEMICAL CONTROL BY CARBOXYLATE GROUPS IN HOMOGENEOUS HYDROGENATION
Brown, John M.,Hall, Stephen A.
, p. 333 - 342 (2007/10/02)
The stereochemistry of hydrogenation of a range of unsaturated cyclohexane-carboxylic acids and their esters has been investigated, employing either bis(1,4-diphenylphosphino)butanerhodium or pyridine(tricyclohexylphosphine)iridium based cationic catalysts in CH2Cl2.For methyl 3-methylcyclohex-2-enecarboxylate, highly selective reduction to the trans-product was achieved in both cases, whereas the isomeric methyl 3-methylenecyclohexanecarboxylate gave appreciable amounts of the cis-isomer.A predominance of trans-isomer was also achieved in the reduction of methyl 4-methylcyclohex-3-ene carboxylate, in a rather slower reaction.Reductions with D2 revealed that considerable isomerisation of the olefinic double bond occurred during hydrogenation.The corresponding unsaturated acids were reduced with moderate to high selectivity but reaction was either very slow, or ceased after a few turnovers.Related cyclohexadienecarboxylates were unreactive to homogeneous hydrogenation with cationic catalysts.
