Enantioenriched acid, ester, and ketone β-phenyl homoenolate synthetic equivalents from N-Boc-N-(p-methoxyphenyl)cinnamylamine

Oxidation of the β-substituted highly enantioenriched aldehydes obtained by hydrolysis of the 3,3-disubstituted enecarbamates affords enantioenriched β-substituted acids and esters. Lithiation of enantioenriched 3,3-disubstituted enecarbamates and subsequent reaction with electrophiles provides vinylically substituted enecarbamates. The use of benzyl and alkyl halide electrophiles affords α-substituted enecarbamates, which can be hydrolyzed to provide enantioenriched β-substituted ketones. Reaction of the lithiated intermediate with ketones affords oxazolidinones, which can be reductively ring-opened with DIBAL and hydrolyzed to provide enantioenriched β-substituted, α′-hydroxy ketones. These transformations demonstrate that the enantioselective lithiation of N-Boc-N-(p-methoxyphenyl)cinnamylamine provides a reactive intermediate which can be a ketone, acid, or ester homoenolate synthon.