Compelling evidence indicates that reactions of pbenylllthium in ether at >lOC" with lchlorocyclopentene, 1-chlorocyclohexene (&), and l-chlorocycloheptene occur predominantly, and probably exclusively, by elimination-addition mechanisms involving cycloalkynes.l In marked contrast, equally compelling evidence indicates that reactions of the 2-halo-3-(2-hydroxyethoxy)cyclohexenes with potassium &-butoxide (KO-;-Bu) in dimethyl sulfoxide (DBO) that give cyclohexenone ethylene ketal and 2,5-dioxabicyclo[4.4.O]dec-7-ene in combined yields of >70$ can be explained on the basis of mechanisms that do not involve a cyclohwe.2 Further, the interesting tricyclic hydrocarbons 2 and 6, which were obtained in yields of 7 and 30s from reactions of 1-bromocyclohexene (2) with KO-z-Bu in DkSd and l-chlorocycloheptene with sodamide in liquid srauonia,4 have been explained as arising from dimerization of intermediate 1,2+ycloalkadienes. This observed diversity of reactions made clear the need of a systematic investigation of reactions of l-halocycloalkenes with a strong base system. Experience tith reactions of substituted l-balocyclohexenes2 indicated that study of reactions of the 1-halocyclohexenes k-2 with KO-k-Bu would be more feasible, and probably more informative, than with either an alkali metal amide or phenyllithium. 1-Chlorocyclohexene (&) was converted to l-lithiocyclohexene,5 and addition of halogen gave 2, bp 72-74"/36 mm,' and 2, bp 53-55'/5 m, in '70% yield.7 Treatment of 1, 2, and 2 in Dk50
at 65" with 1.1 equiv of KO-t=Bu.HO-L-Bu for 30, 3.2 and 2 hr, respectively, (or 2.2 equiv of resublimed KO-i-Ru for <7 min) gave, in addition to a complex mixture of bydrocarbons,8 a 5-X$