A Quantitative Structure-reactivity Relationship In Decarboxylative Claisen Rearrangement Reactions Of Allylic Tosylmalonate Esters

摘要

First-order rate constants have been determined for the decarboxylative Claisen rearrangement reactions at 293 K of substituted methyl (E)-3-phenyl-2-propenyl 2-tosylmalonate esters, which show a linear free-energy relationship indicative of the development of positive charge on the benzylic position in the sigmatropic rearrangement transition-state.rnThe Ireland-Claisen rearrangement continues to be used widely in synthesis as a strategy-level method for the regio-specific and stereoselective formation of carbon-carbon bonds. During the course of our studies of thermal decarboxylative Claisen rearrangement (dCr) reactions of allylic α-tosylesters, we have developed dCr reactions of allylic tosylmalonate esters 1. These substrates may be converted into the decarboxylated rearrangement products at room temperature using both the KOAc-A,O-bis(trimethylsilyl)acetamide (BSA) reagent system developed initially, and modified conditions involving treatment of 1 with DBU and tert-butyldimethylsilyl triflate (TBDMSOTf).