Tetrahedron

Cycloadditions to Pyrrolo [1, 2-c] thiazoles and Pyrazolo [1, 5-c] thiazoles

OB Sutcliffe, RC Storr, TL Gilchrist, P Rafferty

Index: Sutcliffe, Oliver B.; Storr, Richard C.; Gilchrist, Thomas L.; Rafferty, Paul Tetrahedron, 2000 , vol. 56, # 51 p. 10011 - 10021

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Citation Number: 23

Abstract

The pyrrolo [1, 2-c] thiazole generated by dehydration of dimethyl 5-methyl-1H, 3H-pyrrolo [1, 2-c] thiazole-6, 7-dicarboxylate 2-oxide acts as a thiocarbonyl ylide in its cycloaddition to electron deficient alkenes but as an azomethine ylide with electron deficient alkynes. The analogous pyrazolo [1, 5-c] thiazole, generated similarly, acts as a thiocarbonyl ylide with both types of dipolarophile. This behaviour is partially explained by Frontier MO theory.