Organic Letters 2018-04-10

Aroyl Isocyanates as 1,4-Dipoles in a Formal [4 + 1]-Cycloaddition Approach toward Oxazolone Construction

KaitlynE. Eckert, Brandon L. Ashfeld

Index: 10.1021/acs.orglett.8b00656

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Abstract

A formal phosphine-mediated [4 + 1]-cycloaddition between a 1,2-dicarbonyl and an aroyl isocyanate to provide oxazolones bearing a disubstituted C5 center is described. By exploiting the carbene-like reactivity of oxyphosphonium enolates as C1 synthons and aroyl isocyanates as formal 1,4-dipoles, oxazolones and spiroooxindole oxazolones are constructed in high yields (39–99%).