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Communication | Regular issue | Vol 22, No. 2, 1984, pp.245-248
Published online, 1st January, 1970
DOI: 10.3987/R-1984-02-0245
Oxygen Heterocycles by Sulphur Ylide Annulation: Synthesis of 3,4-Dihydro-2H,5H-pyrano[3,2-c][1]benzopyran-5-ones by Dimethylsulphoxonium Methylide

Pierfrancesco Bravo,* Paola Carrera, Giuseppe Resnati, Calimero Ticozzi, and Giancarlo Cavicchio

*Dipartmento di Chimica del Polotecnico, Centro Studio Sostanze Organiche Naturali, C.N.R., Piazza Leonardo da Vinci 32, 20133 Milano, Italy

Abstract

3,4-Dihydro-2-hydroxymethyl-2H,5H-pyrano[3,2-c][1]benzopyran-5-ones are the main products of the reaction of dimethylsulphoxonium methylide on Michael adducts of 4-hydroxycoumarins and α,β-unsaturated ketones. Minor quantities of 3,4-dihydro-2-hydroxymethyl-2H,5H-pyrano[2,3-b][1]benzopyran-5-ones are also sometimes obtained.