PRACTICAL PREPARATION OF BICYCLO[3.2.0]HEPT-3-EN-6-ONES AND IT UTILIZATION IN STEREOSELECTIVE TOTAL SYNTHESIS OF GRANDISOL AND LINEATIN VIA A VERSATILE INTERMEDIATE

New and efficient stereoselective total syntheses have been devised for racemic grandisol and lineatin, two important components of pheromonic blends. They are based on the utilisation of 1,4-dimethylbicyclo[3.2.0]hept-3-en-6-one as a pivotal intermediate. This compound, as well as other bicyclo[3.2.0]hept-3-en-6-ones, are now easily available by a practical bicyclization of the corresponding 3-hydroxy-6-alkenoic acids.