Synthesis of Naturally Occurring Prenylated Benzophenones. Vismiaphenone A, Vismiaphenone B, and Isovismiaphenone B
作者:Ved Prakash Pathak、Rajinder Nath Khanna
DOI:10.1246/bcsj.55.2264
日期:1982.7
2,4,6-Trihydroxybenzophenone on prenylation with 2-methyl-3-buten-2-ol in the presence of (C2H5)2O·BF3 yielded 2,4,6-trihydroxy-3,5-diprenylbenzophenone (3), 2,6-dihydroxy-4-prenyloxybenzophenone, 2,6-dihydroxy-3-prenyl-4-prenyloxybenzophenone, a benzodipyran and 6-benzoyl-5,7-dihydroxy-2,2-dimethyl-3-prenylchroman. 3 on reaction with 2 moles of p-toluenesulfonyl chloride followed by methylation and detosylation gave a naturally occurring benzophenone, vismiaphenone A (12). Cyclodehydrogenation of 6-hydroxy-3,5-diprenyl-2,4-ditosyloxybenzophenone gave 8-benzoyl-2,2-dimethyl-6-prenyl-5,7-ditosyloxy-2H-1-benzopyran, which on detosylation gave another naturally occurring benzophenone, isovismiaphenone B, while cyclodehydrogenation of 3 gave vismiaphenone B, another naturally occurring benzophenone. 2,4-Dihydroxy-6-methoxy-benzophenone on similar treatment with 2-methyl-3-buten-2-ol afforded 12 directly.
2,4,6-三羟基二苯甲酮与
2-甲基-3-丁烯-2-醇在(
C2H5)2O·
BF3存在下进行
苄基化反应,生成
2,4,6-
三羟基-3,5-二
苄基二苯甲酮(3)、
2,6-二羟基-4-苄
氧基
二苯甲酮、
2,6-二羟基-3-
苄基-4-苄
氧基
二苯甲酮、
苯并二
吡喃和6-
苯甲酰基-5,7-二羟基-
2,2-二甲基-3-
苄基苯并二
氢吡喃。3与2摩尔
对甲苯磺酰氯反应,然后
甲基化和
脱甲酰化,生成
天然存在的
二苯甲酮,即维西米阿
苯甲
酮A(12)。6-羟基-3,5-二
苄基-
2,4-二甲酰
氧基
二苯甲酮的环
脱氢反应生成8-
苯甲酰基-
2,2-二甲基-6-
苄基-5,7-二甲酰
氧基-2H-1-
苯并
吡喃,
脱甲酰