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Alkylation of the hippurate esters of trans 2-(p-substituted phenyl)cyclohexanol with benzyl bromide affords phenylalanine derivatives in high chemical yield. The reaction stereoselectivity varies from 20 to >98% depending on the aromatic group in the cyclohexyl auxiliary. A model that correctly predicts the sense of the induction is proposed.

Alkylations of anions derived from dipeptides with a glycine at the C-terminus have been investigated. A hydrocarbon sedition in the N-terminal residue does impart some asymmetric induction. The use of a chiral ester derivative provides the potential for double asymmetric induction and good selectivity. With an aspartyl residue at the N-terminus, problems were encountered due to competing side reactions. The use of an azetidinone could circumvent some of these, but the observed induction was not high.

Dissolving metal reduction of known enone S affords predominantly the racemic form of title ketone ( 3 ) whereas catalytic reduction gives the meso isomer 6 . Neither ketone 3 nor alcohol 4 could be satisfactorily resolved. Asymmetric synthesis of (−)− 3 and (+)− 4 (ee=91 %) was effected from ketone (+)- 13 .

Alkylation of the D-camphor imine of tert -butyl glycinate with secondary allylic and benzylic halides affords products which have high stereochemical purity, particularly at the halogen displacement site.

L'exces diastereoisomere est relie a la densite d'electrons π et aux effets steriques dans l'electrophile

The preparation of 2-carboxylated-1,3-dienes from carbomethoxy vinylphosphonates and 2-mercaptocarbonyl compounds has been shown to give stereoisomeric mixtures. This may be due to the formation of stereoisomers of the intermediate 2,5-dihydrothiophenes and (or) to the occurrence of both modes of disrotatory sulfur dioxide elimination.

Attempted imine formation between 3-hydroxycamphor and tert. butyl glycinate led to 8 the substitution product at the 3-position. Zinc-acetic acid treatment of 8 afforded 3-acetoxycamphor. Alkylation of the imine from from norcamphor and tert. butyl glycinate gave no stereoselection. Alkylation of the imine from from 10-hytdroxymethylcamphor and tert. butyl glycinate gave stereoselectivities inferior to those obtained from the imine of camphor itself ( 1 ) but aldol condensation with benzaldehyde, a reaction not possible with 1, was affected in 71% yield.

L'epoxydation conduit au melange 1:1 des cis- et trans-epoxy-3,4 cyclohexanemethanols et non au stereoisomere trans de facon predominante