RELATIVE RATES OF CLEAVAGE BY ALKOXIDE IONS OF DIPHENYLCYCLOPROPENONE AND OF DIPHENYLTHIIRENE 1,1-DIOXIDE

The rates of reaction of diphenylcyclopropenone (1) with sodium methoxide in methanol, sodium ethoxide in ethanol, and sodium isopropoxide in isopropyl alcohol have been determined at several temperatures. A comparable study has been made with diphenylthiirene 1,1-dioxide (2). In each instance the relative rates were in the order, NaOMe:NaOEt:NaO-i-Pr + 1:2:6. The ratio of rates for 2 to 1 was ca. 5000 to 1. This striking reversal of the usual much more facile attack of base on the carbonyl group than on the sulfonyl group is attributed to a marked conjugative stabilization of 1 as contrasted to a slight conjugative stabilization of 2. © 1969, American Chemical Society. All rights reserved.