Rhodium carbene routes to oxazoles and thiazoles. Catalyst effects in the synthesis of oxazole and thiazole carboxylates, phosphonates, and sulfones

B Shi, AJ Blake, W Lewis, IB Campbell…

Index: Shi, Baolu; Blake, Alexander J.; Lewis, William; Campbell, Ian B.; Judkins, Brian D.; Moody, Christopher J. Journal of Organic Chemistry, 2010 , vol. 75, # 1 p. 152 - 161

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Citation Number: 72

Abstract

Dirhodium tetraacetate catalyzed reaction of α-diazo-β-keto-carboxylates and-phosphonates with arenecarboxamides gives 2-aryloxazole-4-carboxylates and 4-phosphonates by carbene N− H insertion and cyclodehydration. In stark contrast, dirhodium tetrakis ( heptafluorobutyramide) catalysis results in a dramatic change of regioselectivity to give oxazole-5-carboxylates and 5-phosphonates. α-Diazo-β-ketosulfones behave similarly ...