Cross metathesis of several methylenecyclopentane derivatives

The cross metathesis (CM) of several methylenecyclopentane derivatives using Hoveyda–Grubbs second generation catalyst 4 (5–10 mol %) has been studied. Medium to good yields of tetrasubstituted alkenes have been obtained. In the case of 8-methyl-2,5-dimethylene-2,3,5,6-tetrahydro-1H,4H-3a,6a-(methanoiminomethano)pentalene-7,9-dione 2 products from single, double and triple CM were formed. With 8-methyl-5-methylene-5,6-dihydro-3a,6a-(methanoiminomethano)pentalene-2,7,9(1H,3H,4H)-trione 3 a good yield of the CM product was obtained working at 140 °C in xylene for 3 d, showing the high thermal stability of this catalyst. In the CM of diene 2 and enone 3, the main products were always the anti-stereoisomers.