methyl (2R,3R)-4-(6,7-dimethoxy-1-methylidene-3,4-dihydroisoquinolin-2-yl)-2,3-dihydroxy-4-oxobutanoate 在
盐酸 、 magnesium sulfate 作用下,
以
氯仿 为溶剂,
反应 0.5h,
以85%的产率得到methyl (2R,3R,11bR)-3-hydroxy-9,10-dimethoxy-11b-methyl-4-oxo-2,3,6,7-tetrahydro-[1,3]oxazino[2,3-a]isoquinoline-2-carboxylate