((3R,3aS)-7-cyano-1-oxo-1,3,3a,4-tetrahydrobenzo[b]oxazolo[3,4-d][1,4]oxazin-3-yl)methylmethanesulfonate 、
邻苯二甲酰亚胺钾盐 以afforded white solid 0.286 g, yield: 79.71%的产率得到(3S,3aS)-3-((1,3-dioxoisoindolin-2-yl)methyl)-1-oxo-1,3,3a,4-tetrahydrobenzo[b]oxazolo[3,4-d][1,4]oxazin-7-carbonitrile