L-Methylene-2-vinylcyclopentane

Alkynes are generally more reactive than alkenes as enophiles in both inter- and intra-molecular ene reactions. - 6-Octen-l-yne (100) cyclizes to l-methylene-2-vinylcyclopentane (101) on brief heating at 400 Dehydrolinalool (102) undergoes an ene reaction at 200 C to give (103) in quantitative... 

In earlier investigations, asymmetric nickel-catalyzed isomerization and cyclodimerization of methylenecyclopropane was found to give l-methylene-2-vinylcyclopentane44. The nickel catalyst system was prepared by reduction of NiBr2L2 with butyllilhium. With tributylphosphane as ligand a 91% yield of the dimerization product was obtained. With dibromobis(( - )-methyl(phenyl)propylphosphane]nickel and butyllithium, optically active (no enantiomeric excesses given) l-methylene-2-vinylcyclopentane of unknown absolute configuration was obtained in 30% yield. Involvement of a n-allyl intermediate is proposed (loc. cit. 141 in ref 45). 

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