Alkylation of Position C‐5 of Triacetic Acid Lactone by [2,3] Sigmatropic Rearrangement of Sulphonium Ylides

Pedro De March, Marcial Moreno‐Mañas, Isabel Ripoll

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11 Citations (Scopus)

Abstract

Reactions of the 4‐methoxy‐6‐(phenylthiomethyl)‐2H‐pyran‐2‐ones 4 with three different diazo compounds under copper or rhodium catalysis give the corresponding sulphonium ylides, which through [2,3] sigmatropic rearrangement and further prototropy afford the pyrones 6, functionalized at the difficutly accessible position C‐5. Desulphurations of products 6 with deactivated Raney nickel give the pyrones 17–19. The influence of the experimental conditions on the competition between [2,3] sigmatropic and Stevens rearrangement has been studied for the reaction of 4‐methoxy‐6‐(phenylthiomethyl)‐2H‐pyran‐2‐one (4a) and dimethyl diazomalonate. Several products (9, 10, and 11) arising from sulphonium ylides equilibration and radical recombination have been found in addition to the [2,3] sigmatropic and the Stevens rearrangement products 6d and 8. Copyright © 1987 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim
Original languageEnglish
Pages (from-to)1413-1419
JournalChemische Berichte
Volume120
Issue number8
DOIs
Publication statusPublished - 1 Jan 1987

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