An asymmetric synthesis of (+)-grandisol, a constituent of the aggregation pheromone of the cotton roll weevil, via a kinetic resolution

A novel approach to the asymmetric synthesis of(+)-grandisol, (1R,2S)-isopropenyl-1-methylcyclobutaneethanol, involves the use of catalytic kinetic resolution of a primary allylic alcohol, [( 1RS,5SR)-5-methylbicyclo[3.2.0]hept-2-en-2-yl] methanol. The allylic alcohol is prepared in four steps from simple achiral materials involving the use of a modified Shapiro reaction. The resolved alcohol (95% eel is then reduced in two steps to the corresponding methyl alkene, (1S,5R)-2,5-dimethylbicyclo[3.2.0]hept-2-ene. This alkene is converted to (+)-grandisol (95% eel, in three steps, by modified literature procedures.