Introduction of a 3-alkoxycarbonyl-2-propenyl group at the ortho position of phenol and naphthol via .ALPHA.-aryloxy-.GAMMA.-butyrolactone. Application to syntheses of (.+-.)-nanaomycin A and a 1-anthracenone.
作者:EIICHI YOSHII、TADASHI KOMETANI、KEIICHI NOMURA、YOSHIO TAKEUCHI、SHINJIRO ODAKE、YOSHIHIRO NAGATA
DOI:10.1248/cpb.32.4779
日期:——
Introduction of a (γ-alkoxycarbonyl) allyl group at the 2 position of 1-naphthol was achieved by a sequence of reactions involving a Claisen rearrangement, as illustrated in Chart 1, in overall yields of 62% (via 2a) and 50% (via 2b). By using the same technique, 5-methoxy- and 4, 5-isopropylidenedioxy-1-naphthols and 4-methoxyphenol were converted to the corresponding 4-aryl-2-butenoates (6a, b and 10), which underwent base-catalyzed cyclization to give dihydrofurans (7a, b and 11). Compounds 7a, b were readily transformed into (±)-nanaomycin A (14). 8, 10-Dimethoxy-1-anthracenone (19) was prepared from 6a in 77% yield by a standard method.
如图 1 所示,通过一系列涉及克莱森重排的反应,在 1-萘酚的 2 位引入了(γ-烷氧羰基)烯丙基,总产率为 62%(通过 2a)和 50%(通过 2b)。通过使用相同的技术,5-甲氧基和 4,5-异亚丙基二氧基-1-萘酚和 4-甲氧基苯酚被转化成相应的 4-芳基-2-丁烯酸酯(6a,b 和 10),这些化合物经过碱催化环化生成二氢呋喃(7a,b 和 11)。化合物 7a、b 很容易转化为 (±)- 纳米霉素 A (14)。8,10-二甲氧基-1-蒽酮(19)由 6a 以标准方法制备,收率为 77%。