(1R,2R)-2-((R)-1-amino-2,2-difluoro-3-hydroxy-1-methyl-propyl)-cyclopropane-carboxylic acid ethyl ester 、
溴化氰 以yielded the (1R,2R)-2-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-cyclopropanecarboxylic acid ethyl ester (88% yield) as a white solid的产率得到(1R,2R)-2-((R)-2-amino-5,5-difluoro-4-methyl-5,6-dihydro-4H-[1,3]oxazin-4-yl)-cyclopropanecarboxylic acid ethyl ester