Metal-mediated Variants of the Passerini Reaction: A New Synthesis of 4-Cyanooxazoles

Abstract

When the combination of zinc triflate and chlorotrimethylsilane is substituted for a Brønsted acid, the classic Passerini reaction of carbonyl compounds with t-butyl isonitrile affords an efficient 1:2 condensation product leading to β-hydroxy-α-cyano­enamines 17a-f, which can be transformed into 5-substituted-4-cyanooxazoles­ 8a-f in one step. In contrast to the corresponding Ti-mediated condensations of carbonyl compounds with t-butyl isonitrile, no cyanohydrins are formed.

Key words

oxazole - Passerini - condensation - isonitrile - combinatorial chemistry

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