Thermalrearrangement of mono-, di-, and triphenyl-substituted ketene ethylene acetals was studied. Pyrolysis of all of these acetals provided phenyl-substituted tetrahydro-2-furanones as a major product. The more phenyl groups substitute on the ketene acetal skeleton, the lower reaction temperature was required for the rearrangement. In the cases of the diphenylketene acetals at high temperatures
Diastereoselective Synthesis of γ‐Lactones through Reaction of Sulfoxonium Ylides, Aldehydes, and Ketenes: Substrate Scope and Mechanistic Studies
作者:Nicholas J. Peraino、Mukulesh Mondal、Han‐Jen Ho、Antoine Beuque、Evan Viola、Melanie Gary、Kraig A. Wheeler、Nessan J. Kerrigan
DOI:10.1002/ejoc.202001233
日期:2021.1.8
The reaction of sulfoxonium ylides, aldehydes, and disubstituted ketenes provides access to γ‐lactones in moderate to excellent yields with moderate to good diastereoselectivity favoring the trans‐diastereomer (dr up to 92 : 8). A [3,3]‐sigmatropic rearrangement is proposed to be the key mechanistic step.