Intermolecular Dipolar Cycloaddition Reactions of 5H,7H-Thiazolo[3,4-c]oxazol-4-ium-1-olates

Abstract

(5R)-3-Methyl-5-phenyl-5H,7H-thiazolo[3,4-c]oxazol-4-ium-1-olate was generated in the presence of a range of dipolarophiles. The intermolecular 1,3-dipolar cycloaddition of this mesoionic species led to the synthesis of chiral 1H-pyrrolo[1,2-c]thiazole derivatives 7a, 7b, 8, 14, 18, 19 and 20. In the reaction with methyl and ethyl vinyl ketone, spiro compounds 9 and 15 were also obtained. The structure of compound 15 was determined by X-ray crystallography.