Bismuth(<scp>iii</scp>)-catalyzed bis-cyclization of propargylic diol-esters: a unified approach for the synthesis of [5,5]- and [6,5]-oxaspirolactones
作者:Digambar A. Kambale、Balasaheb R. Borade、Ravindar Kontham
DOI:10.1039/d1ob00974e
日期:——
Herein we disclose an unprecedented intramolecular cascade strategy for the construction of α,β-unsaturated [5,5]- and [6,5]-oxaspirolactones that capitalizes on the π-electrophilic Lewis acid-catalyzed 5-exo-dig or 6-exo-dig mode of cyclization of propargylic diol esters, followed by dehydration and spirolactonization steps. Moreover, semi-protected substrates also delivered the respective oxaspirolactones
在此,我们公开了一种前所未有的分子内级联策略,用于构建 α,β-不饱和 [5,5]- 和 [6,5]-氧杂螺内酯,该策略利用 π-亲电子路易斯酸催化的 5 -exo-dig或 6-炔丙基二醇酯环化的exo-dig模式,然后是脱水和螺内酯化步骤。此外,半保护底物还可以在最佳反应条件下以相同的容易程度和可观的收率递送各自的氧杂螺内酯。