One-Step Synthesis of delta-Lactones Having Biological Activity by Remote Carbonylation

在这项工作中，一个新的简单的方法来合成delta-内酯已被追求。利用四乙酸铅诱导醇类氧化，实现了饱和醇与一氧化碳合成三角内酯的新方法。这种远端羰基化对于碳是伯碳或仲碳的伯碳和仲碳醇是很普遍的。如果醇同时具有伯碳和仲碳，则一氧化碳以24:1的比例与仲碳结合。该反应序列可以成功地应用于一步合成木蜂性信息素，从市售的光学纯(R)-(-)-2-己醇和一氧化碳开始。另一方面，1,2-二醇型底物的反应导致β -断裂而不是羰基化。这表明，为了将这种远程羰基化应用于甲羟内酯的合成，需要在构建关键的三角内酯骨架后引入-羟基。

In this work, a novel straightforward method for the synthesis of delta-lactones has been pursued. Taking advantage of the lead tetraacetate-induced oxidation of alcohols, a novel delta-lactone synthesis from saturated alcohols and CO was achieved. This remote carbonylation is quite general for primary and secondary alcohols whose delta-carbons are primary or secondary. In case of an alcohol having both primary and secondary delta-carbons, carbon monoxide is incorporated at the secondary carbon in a 24 : 1 ratio. The reaction sequence can be successfully applied to a one-step synthesis of a carpenter bee sex pheromone starting from commercially available, optically pure (R)-(-)-2-hexanol and carbon monoxide. On the other hand, attempted reaction of a 1,2-diol type substrate resulted in beta-fragmentation rather than carbonylation. This suggests that for an application of this remote carbonylation to the synthesis of mevalonolactone, beta-hydroxy group should be introduced after constructing the key delta-lactone skeleton.