An effective synthesis of 2, 3-disubstituted 2-cyclopentenones involves C4→ C3 ring contraction of the readily available 1, 2-disiloxycyclobutene followed by thermal C3→ C5 ring enlargement of trimethylsiloxyvinyl-cyclopropanes. To illustrate the convenience of this new approach the total syntheses of 2-methyl-3-p-tolyl-2-cyclopentenone, dihydrojasmone. and cis-jasmone are reported.
