SYNTHETIC APPLICATIONS OF CYCLIC ALPHA-CHLORO ETHERS AND THIOETHERS .8. DECARBETHOXYLATION AND RING-OPENING REACTIONS OF 2-TETRAHYDROFURANYL-SUBSTITUTED ESTERS, 2-TETRAHYDROTHIENYL-SUBSTITUTED ESTERS, AND 2-(1,3-DITHIANYL)-SUBSTITUTED ESTERS

The course of decarbethoxylation reactions of 2-tetrahydrofuranyl-, 2-tetrahydrothienyl-, and 2-(1, 3-dithianyl)-substituted malonic esters 1-3 with NaCl/H2O in Me2SO is shown to be dependent on the nature of the substituents at the α-carbon atom. In several instances, selective decarbethoxylation provides the monoesters 4-6. In other cases, stereoselective ring-opening reactions take place, leading to mixtures of α,β- and β,Ϝ-unsaturated esters. In the absence of H2O, the cyclopropyl-substituted ester 13a (R = H) is formed. Anions obtained by deprotonation of monoesters 4-6 and diesters 1-3 (R = H) undergo similar ring-opening reactions. © 1979, American Chemical Society. All rights reserved.