Addition of arenesulphenyl chlorides to 2-methylenebicyclo[2.2.1]hept-5-ene: effect of increasing electron demand upon the rate and product determining transition states

Abstract

The rates and products of addition of a series of s~xteen arenesulphenyl chlorides to 2-methylenebicyclo[2.2. Ilhept-Sene, 7, and the E , Z isomeric 2-ethylidenebicyclo[2.2. Ilhept-5-enes, 8 and 9, have been determined in methylene chloride solution. The major species from attack on 7 is always endo-3-arylthio-I-chlorornethyltricyclo[2.2. 1.02~6]heptane, the product of exo attack upon the endocyclic double bond with homoallylic participation of the exacyclic n system. N o evidence was found for initial electrophilic attack upon the exocyclic double bond. Chem. 58, 1021Chem. 58, (1980 In two previous articles (1,2) we have discussed intermediates of type 3 and 4 instead of the comthe effect of increasing electron demand (3) upon monly accepted sulphonium ions 5 and 6 (4). the product determining transition state in the In regard to this latter point, we observed a reaction of arenesulphenyl chlorides with car-stabilizing interaction only in the case of 2,4-bon-carbon double bonds and single bonds using dinitrobenzenesulphenyl chloride, presumably as a respectively bicyclo[2.2.l]hepta-2.5-diene, 1, and result of the dual electron withdrawal of both nitro tetracycl0[3.2.0.0~.~.0~.~]heptane, 2, as substrates. groups, since in the presence of more electron donating substituents in the para position one observes only the electron withdrawing properties of the ortho nitro group.The aim of these studies was two-fold. Firstly, we desired to ascertain the effect of varying the elec-