SOLVENT EFFECTS IN THE CONVERSION OF PHENYLDIAZOMETHANE INTO STILBENE AND SPIROOXETANE IN THE REACTION WITH CHLORANIL

Article abstract of DOI:10.1246/bcsj.55.904

A stereochemical study was made of the reaction of phenyldiazomethane(1) with chloranil(2) at 20 deg.C in 28 aprotic solvents.The products were trans-spirooxetane(4) and cis-trans mixtures of stilbene(3) (ca. 2-5 times cis-rich).The molar ratios of cis-3 to the sum of the trans-3 and 4 tended to increase, whereas the 4 to trans-3 ratios decrease with the increase in the solvent basicity and polarity.These effects of solvents on the product distributions were interpreted in terms of the effects of the solvent basicity and polarity on the stereoselective formation of the diazonium betaine intermediate and on the conformational isomerism.Moderately successful linear-free-energy(LFE) relationships were established for these product ratios with the aid of the combination of the empirical solvent basicity parameter, D_?, and the Kirkwood function, f(ε), or E_T values as the solvent polarity parameters.