471-89-6Relevant academic research and scientific papers
Syntheses of the enantiomers of γ-cyclogeranic acid, γ-cyclocitral, and γ-damascone: Enantioselective protonation of enolates
Fehr,Galindo
, p. 539 - 552 (2007/10/02)
(R)- and (S)-γ-cyclogeranic acid ((R)- and (S)-9, resp.) were obtained by resolution of the racemate, and their absolute configurations determined by chemical correlation. The γ-acids (R)- and (S)-9 were converted into (R)- and (S)-methyl γ-cyclogeranate ((R)- and (S)-6, resp.), and (R)- and (S)-γ-damascone ((R)- and (S)-5, resp.). A more direct entry to (R)- and (S)-9 consisted in the enantioselective protonation of a thiol ester enolate with (-)- or (+)-N-isopropylephedrine ((-)- or (+)-20) and subsequent hydrolysis of the (R)- and (S)-S-phenyl γ-thiocyclogeranate ((R)- and (S)-24, resp.; 97% ee). The esters (R)- and (S)-24 were also used as precursors of (R)- and (S)-γ-damascone ((R)- and (S)-5, resp.). Alternatively, (S)-5 (75% ee) was obtained by enantioselective protonation of ketone enolate 29 with (-)-N- isopropylephedrine ((-)-20). Organoleptic evaluation demonstrated that the (S)-enantiomers of methyl γ-cyclogeranate and γ-damascone are markedly superior to their (R)-enantiomers.
Synthesis of (+/-)-trixagol by an electrophilic cyclization of an allylsilane
Armstrong, Rosemary J.,Weiler, Larry
, p. 2530 - 2539 (2007/10/02)
1,5-Dienes containing an allylsilane are cyclized by Lewis acids to methylenecyclohexanes.The trimethylsilyl group exerts a strong activating and directing influence on the regioselectivity of this cyclization.The monocyclic compound 10 was converted into the diterpene, (+/-)-trixagol (3).
