Johny M, Philip RM, Rajendar G. Highly Regio- and Stereoselective Intramolecular Rearrangement of Glycidol Acetal to Alkoxy Cyclic Acetals.
Org Lett 2022;
24:6165-6170. [PMID:
35960602 DOI:
10.1021/acs.orglett.2c02397]
[Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new class of highly regio- and stereoselective intramolecular rearrangements of glycidol acetals to produce alkoxylated 1,3-dioxolane/1,3-dioxane is demonstrated. Selective Lewis acid activation of acetal generates an oxocarbenium ion that initiates the epoxide ring-opening event, giving the bicyclic [3,1,0]epoxonium ion intermediate that undergoes exo/endo-selective opening by a tethered alkoxide. Mechanistic insights into preferential acetal activation over the epoxide were obtained by crossover experiments. The method was applied in the total synthesis of parvistone B and its 8-ethoxy analogue.
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