Sigmatropic 1.5-hydrogen shift and concomitant cyclopropane bond cleavage on thermolysis of -1-isopropenyl-4-methylene [2.x]alkanes into 1-methylene-(3′-methylbut-2′-enyl)-cycloalk-2-enes
Sigmatropic 1.5-hydrogen shift and concomitant cyclopropane bond cleavage on thermolysis of -1-isopropenyl-4-methylene [2.x]alkanes into 1-methylene-(3′-methylbut-2′-enyl)-cycloalk-2-enes