Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India.
Org Biomol Chem. 2021 Aug 5;19(30):6618-6622. doi: 10.1039/d1ob00974e.
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 with the same ease and in appreciable yields under optimal reaction conditions.
在此，我们揭示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-亲电路易斯酸催化的丙炔二醇酯的 5-endo-或 6-endo-环化，随后进行脱水和螺内酯化步骤。此外，在最佳反应条件下，半保护底物也以相同的简便性和可观的收率得到相应的氧杂螺内酯。
