Stereoselective Synthesis of Unnatural β-Amino Acids from Nitroethane via 5,6-Dihydro-4H-1,2-oxazin-3-ylacetates

Abstract

Stereoselective Synthesis of Unnatural b-Amino Acids from Nitroethane via 5,6-Dihydro-4H-1,2-oxazin-3-ylacetates S t e r e o s e l e c t i v e S y n t h e s i s o f U n n a t u r a l b -A m i n o A c i d s f r o m N i t r o e t h a n eAbstract: The reduction of easily available methyl 5,6-dihydro-4H-1,2-oxazin-3-ylacetates provides an efficient route to different diastereomerically pure unnatural b-amino acids. A two-step protocol including reduction of the C=N bond of the initial oxazine with sodium cyanoborohydride during the first step and hydrogenation of the N-O bond during the second step produced the target b-amino acid esters with higher stereoselectivity than obtained with conventional catalytic hydrogenation.