Synthesis of stereoisomers of artemisia and chrysanthemum bis(acetylenic) enol ether spiroacetals
An 11-step synthesis is described of two diastereomeric candidates for a bis(acetylenic) enol ether spiroacetal isolated from Chrysanthemum boreale. Key steps in the synthetic route include spiroacetal lactone alkylidenation and subseqent modified Cadiota-Chodkiewicz cross-coupling to install the bis(acetylenic) enol ether functionality. From NMR comparisons, neither of the candidates, whose structures were confirmed by single-crystal X-ray diffraction, correspond to the natural product, and a proposal for the correct structure is put forward.
Wu, Boshen,Feast, George C.,Thompson, Amber L.,Robertson, Jeremy
A short and efficient synthesis of the polyacetylene natural product deca-4,6,8-triyn-1-ol
A practical and efficient four-step synthesis of the natural product deca-4,6,8-triyn-1-ol has been achieved beginning with (triisopropylsilyl)acetylene. This trialkyne has potential utility as a key intermediate for the total synthesis of the antitumor butenolide natural product vernoniyne.
Machado, Vanessa Rocha,Biavatti, Maique Weber,Danheiser, Rick L.