摘要:
Petasis reactions of substituted styrenylboronic acids and glyoxylic acid, employing tert-butylsulfinamide as the 'amine' component, proceed with high stereoselectivity to produce beta,gamma-dehydrohomoarylalanine derivatives. Subsequent asymmetric dihydroxylation under neutral conditions gives the corresponding protected beta,gamma-dihydroxyhomoarylalanines with up to 15:1 dr. The method has been exploited in the efficient, stereoselective synthesis of protected beta,gamma-dihydroxyhomotyrosine, a component of the antifungal cyclic peptide echinocandin B.