(2S,3aR,5R,6S,6aR)-5-((R)-2,2-Dimethyl-[1,3]dioxolan-4-yl)-6-hydroxy-2-methyl-tetrahydro-furo[2,3-d][1,3]dioxole-2-carboxylic acid methyl ester 生成 methyl (2S,3aR,5S,6S,6aR)-5-[(4R)-2,2-dimethyl-1,3-dioxolan-4-yl]-2-methyl-6-trityloxy-3a,5,6,6a-tetrahydrofuro[2,3-d][1,3]dioxole-2-carboxylate