Alkynes From Furans: A General Fragmentation Method Applied to the Synthesis of the Proposed Structure of Aglatomin B. Issue 14 (28th February 2018) - Deng, Jiachen
Abstract: Furans are versatile synthons in organic chemistry. Described is a general method for transforming furans into alkynes by dual C−C double‐bond cleavage. The reaction is proposed to proceed by sequential [4+2] cycloaddition between furan and singlet oxygen and a formal retro‐(3+2) fragmentation of the endoperoxide intermediate. A wide array of furans, including those derived from sapogenins, are amenable to this reaction, thus providing the corresponding alkynoic acids in up to 88 % yields. The synthetic utility was demonstrated by a seven‐step synthesis of the proposed structure of a pregnane natural product, aglatomin B, from a known intermediate. Abstract : A general fragmentation method that transforms furans into alkynes, by dual C−C double‐bond cleavage, is described. The reaction is proposed to proceed by sequential [4+2] cycloaddition between furan and singlet oxygen, and a formal retro‐(3+2) fragmentation of the endoperoxide intermediate. The synthetic utility was demonstrated by a seven‐step synthesis of the proposed structure of aglatomin B.