A cyclization of .BETA.-arylethylisocyanates to 3,4-dihydroisocarbostyrils.
作者:BUNSUKE UMEZAWA、OSAMU HOSHINO、SHOHEI SAWAKI、KAZUHIKO MORI
DOI:10.1248/cpb.28.1003
日期:——
A β-arylethylisocyanate derived from β-(3, 4-methylenedioxyphenyl) (3a)-, β-(3, 4-dimethoxyphenyl) (3b)-, β-(3, 4, 5-trimethoxyphenyl) (3c)- or β-(3-methoxyphenyl) (3d)-propionic acid was treated with anhydrous phosphoric acid at room temperature to give, in moderate yield, 6, 7-methylenedioxy (4a)-, 6, 7-dimethoxy (4b)-, 6, 7, 8-trimethoxy (4c)-, or 6-methoxy (4d)- and 8-methoxy (4d')-3, 4-dihydroisocarbostyrils. In the case of β-(4-benzyloxy-3-methoxyphenyl) (3e)- or β-(3-benzyloxy-4-methoxyphenyl) (3f)-propionic acid, however, only 8-benzyl-7-hydroxy-6-methoxy (4e)- or 5-benzyl-6-hydroxy-7-methoxy (4f)-3, 4-dihydroisocarbostyril, respectively, was obtained in low yield.
一种由β-(3, 4-亚甲基二氧基苯) (3a)-、β-(3, 4-二甲氧基苯) (3b)-、β-(3, 4, 5-三甲氧基苯) (3c)-或β-(3-甲氧基苯) (3d)-丙酸衍生的β-芳基乙异氰酸酯在室温下与无水磷酸处理,可以适度产率获得6, 7-亚甲基二氧基 (4a)-、6, 7-二甲氧基 (4b)-、6, 7, 8-三甲氧基 (4c)-或6-甲氧基 (4d)-和8-甲氧基 (4d')-3, 4-二氢异氟啶。然而,对于β-(4-苄氧-3-甲氧基苯) (3e)-或β-(3-苄氧-4-甲氧基苯) (3f)-丙酸,仅分别获得了8-苄基-7-羟基-6-甲氧基 (4e)-或5-苄基-6-羟基-7-甲氧基 (4f)-3, 4-二氢异氟啶,产率较低。