Photolysis of α-diazocyclopentanones. Ring contraction to functionalised cyclobutanes and synthesis of junionone, grandisol and planococcyl acetate
作者:Arun Ghosh、Ujjal K. Banerjee、R.V. Venkateswaran
DOI:10.1016/s0040-4020(01)88398-8
日期:1990.1
a known precursor of grandisol (1). The diazoketone 28, on photolysis yielded a mixture of cyclobutane carboxylates 29 and 30. Conversion of the trans acid 31 to a methyl ketone followed by oxidative functionalisation of the phenyl group gave the keto ester 36 which was isomerised under acid catalysis to 37, which in optically active form had been a precursor to (-) grandisol. Photolysis of diazoketone
重氮酮19在甲醇中的光解提供了环丁烷羧酸酯20。在碳酸氢钠水溶液-THF中的光解以更好的产率提供了酸21。酯的还原,随后的氧化和随后的Wittig反应提供了±junionone (3)。重氮酮24的光解导致环丁烷羧酸酯25的1:1混合物。用氢碘酸处理相应的羧酸提供了双环内酯27,其是大新醇(1)的已知前体。重氮酮28在光解后产生环丁烷羧酸盐29的混合物和30。将反酸31转化为甲基酮,然后对苯基进行氧化官能化,得到酮酯36,其在酸催化下被异构化为37,其以光学活性形式是(-)大丁香酚的前体。重氮酮38的光解提供了2∶1比例的环丁烷羧酸盐39和40。用甲基锂处理并随后乙酰化的相应的酸混合物提供了乙酸酮基酯43和44,从而导致乙酸链烷酰基酯的正式合成(4)。