Electrophilic cleavage of cyclopropanes. The areneselenenylation of tetracyclo[3.2.0.0^2,7.0^4,6]heptane (quadricyclene)^1,2

Abstract

. 58, 1005 (1980). The reaction of benzeneselenenyl chloride with tetracycI0[3.2.0.0'~.0~.'3heptane (quadricyclene) yields, under conditions of kineticcontrol, adducts of both 1.3-and conjugative I ,6-addition, the latter being formed preferentially. Electrophiliccleavage of the cyclopropane ring occurs by both retention and inversion of configuration. In agreement with the known propensity for bond cleavage in this system only the C5-C6 and/or the CI-C7 bonds are broken. The rate of cyclopropane ring cleavage is found to follow second order kinetics, first order in quadricycleneand first order in selenenyl chloride; kOb, = 1850vs. 12 300drn3 mol-I s-I for bicyclo[2.2. Ilhepta-2,5-diene at 24.5"C in methylene chloride solvent. The use of nucleophilic solvents such as HOAc, CH,OH, and CH,CN gives products of solvent-incorporation, preferentially via 1,3-addition. Electrophilic additions of areneselenenyl halides benzeneselenenyl chloride with 2 substantiate (1) and pseudohalides (2) to carbon-carbon double these expectations (5); the specific rate constants and triple bonds have received considerable inter-for the reactions of 2 and the less strained olefin, est of late. No attention has, however, been de-cyclohexene, with benzeneselenenyl chloride in voted to the possible reaction of these electrophiles methylene chloride solution at 25°C being, respecwith carbon-carbon single bonds in, for example, tively, 12 400 and 272 dm3 mol-' s-I. cyclopropanes. In this article we wish to report Results the results of a detailed examination of the cyc~opropane ring cleavage of tetracyclo-The reaction of 1 with benzeneselenenyl chloride [3.2.0.02,7.04,6]heptane, 1, using benzeneselenenyl was initially studied in methylene chloride solution as the electrophilic The of at 23-25°C. The reaction is essentially instanta-1 as substrate was made from a consideration of its "eOUS, the deep red coloration the selenenyl anticipated high reactivity with selenium elec-chloride solution disappearing immediately upon trophiles. ~~~h 1 and the isomeric olefin bicycle-mixing. Immediate lH and 13C nmr analysis of the [2.2. ]]hepta-2,5-diene, 2, normally display high crude product mixture, after w 0 r k -u~~ shows the reactivity (3), presumably as a result of their large presence of four adducts 3-6 in the proporstrain energies, 78.7 and 25.6 kcal mol-', respec-tions 62:30:5:3. No evidence was found for prodtively (4). Earlier studies involving the reaction of

The Carbonyl Group as Homoconjugated Electron‐Releasing Substituent. Regioselective electrophilic additions at bicyclo[2.2.1]hept‐5‐en‐2‐one, bicyclo[2.2.2]oct‐5‐en‐2‐one, and derivatives

“…'H-NMR and "C-NMR data are given in Tables 1 and 2. [37] and Bicyclo[2.2.l]hepta-2,S-diene [38], tl The 1st fraction contained PhSeSePh, the 2nd 10.0 g (67%) of 22 (yellow oil, after evaporation). This fraction was directly used for the preparation of 43 (see below).…”

Ring-opening reactions of cyclopropanes. Part 7.1 Selenenylation and cyanoselenenylation of ethyl 2,2-dimethoxycyclopropanecarboxylates

“…It also appeared interesting to compare the data for areneselenenylation with those previously reported for arenesulfenylation since the reactivity of selenenyl compounds is often compared with that of their sulfenyl analogues. [6][7][8] Fig. 1 Both benzeneselenenyl chloride 3 and phenyl selenocyanate 4 add to alkenes giving rise to interesting compounds.…”