Photochemistry of 7-acetoxybenzopyran derivatives. Synthesis of eupatoriochromene and encecalin
作者:Miguel A. Miranda、Jaime Primo、Rosa Tormos
DOI:10.1016/s0040-4020(01)89221-8
日期:1989.1
The photolysis of the 7-acetoxybenzopyran derivatives 1a-5a has been carried out. Chromene 1a was found to undergo extensive photopolymerization. Chromanone 2a underwent a rather inefficient photo-Fries rearrangement to the 6 - and 8 - acetyl derivatives 2b and 2c. Diacetoxychromene 3a gave the unsaturated ketone 8 as the main product, besides its deacetylation analogue 9 and chromanone 11. Diacetoxychroman
7-乙酰氧基苯并吡喃衍生物1a-5a的光解已经进行。发现Chromene 1a进行了广泛的光聚合。Chromanone 2a经历了效率低下的Photo-Fries重排反应,生成6-和8-乙酰基衍生物2b和2c。Diacetoxychromene图3a,得到不饱和酮8作为主要产物,除了它的脱乙酰化类似物9和二氢吡喃酮11。二乙酰氧基铬烷4a提供了四种C-乙酰基产物的混合物:1b,1c,2b和2c,以及Chromene 1a和苯并二氢吡喃酮2a。最后,苯并二氢吡喃5a的辐射产生了两种可能的光炸产物5b(43%)和5c(52%)的混合物。讨论了以上结果的机理意义,特别强调了与吡喃环,烯醇酯和苄基酯部分相比,苯酯的光反应性。这些转化的合成应用通过制备紫杉烯酮1b和encecalin 1e进行了说明。