Synthesis of the 2-Alkenyl-4-alkylidenebut-2-eno-4-lactone (=α-Alkenyl-γ-alkylidenebutenolide) Core Structure of the Carotenoid Pyrrhoxanthinvia the Regioselective Dihydroxylation of Hepta-2,4-diene-5-ynoic Acid Esters
作者:Joachim Schmidt-Leithoff、Reinhard Brückner
DOI:10.1002/hlca.200590149
日期:2005.7
A new strategy for the stereoselective synthesis of 4-alkylidenebut-2-eno-4-lactones (=γ-alkylidenebutenolides) with (Z)-configuration of the exocyclic CC bond at C(4) was developed. It is exemplified by the synthesis of 4-alkylidenebutenolactone 31 (Scheme 4), which constitutes a substructure of the carotenoids pyrrhoxanthin (1) and peridinin. The formation of the precursor 4-(1-hydroxyalkyl)butenolactone
提出了一种新的立体选择性合成4-亚烷基丁-2-烯-4-内酯(= γ-亚烷基丁烯内酯)的新策略,该构型在C(4)处具有环外CC键的(Z)-构型。以4-亚烷基丁烯内酯31(方案4)的合成为例,其构成类胡萝卜素黄嘌呤黄嘌呤(1)和苦配素的亚结构。前体4-(1-羟烷基)丁烯内酯29的形成是通过27(29)的prop-2-yn-1-ol部分的环羰基化或异亚丙基保护的炔酸酯26(28)的加氢苯乙烯基化来完成的。),然后进行转缩醛化/酯交换反应(30)。通过抗选择性Mitsunobu脱水形成29-亚烷基丁烯酸内酯29 31。