Synthesis of alpha(2,2),beta(3)-Diamino Acids by Double Stereodifferentiation Aldol Addition of Oxazolidinone Enolates to N-(tert-Butylsulfinyl) Imines

A novel application of Seebach's "SRS" synthetic principle works efficiently when conformationally restrained trisubstituted chiral alpha(2,2), beta(3)-diamino acids are synthesized by double stereoinduction reactions of chiral oxazolidinone enolates with N-sulfinyl aldimines. Two stereoisomers were isolated in a form of 1'-(sulfinylamino)oxazolidinones and bicyclic 1H, 3H-imidazo[1,5-c]oxazole-1,5(6H)-diones, from which the alpha(2,2), beta(3)-diamino acids are obtained by selective deprotection methodologies. Among a variety of highly functionalized diamino acids, this highly diastereoselective protocol provides a synthetic route for yet unreported C-glycosyl and alpha-nucleoside diamino acids.