Cyclopent-2-en-1-ones from [3 + 2]-annulation of 3-ethoxycarbonyl-2-propenylidene(triphenyl)phosphorane and glyoxals: Synthesis of cis-jasmone

Article abstract of DOI:10.1016/0040-4039(96)01213-0

3-Ethoxycarbonyl-2-propenylidene(triphenyl)phosphorane (2) reacted with glyoxal monohydrates (5) to give 2-substituted 5-ethoxycarbonylcyclopent-2-en-1-ones (6) by [3 + 2]-annulation reaction in the presence of a base. Compounds 6 were easily converted to 2-substituted cyclopent-2-en-1-ones by deethoxycarbonylation. An application of the annulation to synthesis of cis-jasmone is also described.