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Updated: Jul 29, 2026

Metal-free Synthesis of Ynones from Acyl Chlorides and Potassium Alkynyltrifluoroborate Salts
Published on: February 24, 2015
Hydrazulene ring systems via heteroatom-assisted [1,2]-shift of oxonium and sulfonium ylides
1Department of Chemistry, University of Alberta, Edmonton, AB, Canada T6G 2G2.
Abstract:
[reaction: see text] Cyclic mixed acetals with pendant diazoketone side chains undergo rearrangement to ether-bridged cycloheptane ring systems on treatment with Cu(hfacac)(2). Stevens [1,2]-shift of an oxonium ylide furnishes the major product (7), in some cases accompanied by minor amounts of a product (8) resulting from [1,2]-shift of a sulfonium ylide. In the subsequent sulfur-triggered cleavage of the bridging ether, the desired bicyclo[5.3.0]heptene was obtained, along with the product of novel S(N)2' attack on the resulting allylic ketal.
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