ORGANIC SULFUR MECHANISMS .36. CYCLOPROPANESULFONYL CHLORIDE - ITS MECHANISMS OF HYDROLYSIS AND REACTIONS WITH TERTIARY-AMINES IN ORGANIC MEDIA

Cyclopropanesulfonyl chloride (1) has been synthesized and its reactions examined to see if the three-membered ring leads to unusual reactions in either 1 or the corresponding sulfene, cyclopropanethione S,S-dioxide (2). pH-rate profiles, primary kinetic isotope effects (KIE's), and pH-product ratio experiments are in full agreement with mechanisms of hydrolysis of 1 like those of a simple alkanesulfonyl chlorides (J. Am. Chem. Soc. 1992,114,1743-1749), specifically, (a) below pH 7.2 by S(N)2-S reaction with water and (b) above pH 7.3, elimination by hydroxide to form the sulfene (2) which is trapped by (i) water below pH 12.0 and (ii) hydroxide above pH 12.0. The products of the reaction of cyclopropanesulfonyl-1-d chloride (9) with triethylamine and 2-propanol in dichloromethane indicate that most of the reaction goes via 2; the analogous reaction with trimethylamine apparently proceeds by a direct formation of the sulfonylammonium chloride (14) which then yields the alpha-deuterated N,N-dimethyl sulfonamide (12, R = Me). The evident sulfene formation processes in the reaction of triethylamine with ethanesulfonyl, 2-propanesulfonyl, and cyclopropanesulfonyl chlorides show very low primary KIE's (<1.5), pointing to highly product-like transition states. Reaction of 1 with an enamine (1-pyrrolidino-2-methylpropene, 20) in the presence of a base in either water or dichloromethane gave cyclopropanesulfonpyrrolidide (23) and an aldehyde adduct (24), but no four-membered cycloadduct (21).