CYCLOCONDENSATION OF 2-(3-THIENYL)SUBSTIT UTED O-ALKYL GLYCOLOHYDROXAMIC ACIDS TO 5,6-DIHYDRO-6AH-THIENO[2,3-B]PYRROL-5-ONES

Dicyclohexylcarbodiimide converts the O-alkyl glycolohydroxamic acids 4A, 4B into 5,6-dihydro-6aH-thie-no[2,3-b]pyrrol-5-ones 6A, 6B, the fo rmation of which depends on the nature of the C2-substituents. Acid-ca talyzed methanolysis of 6Ba, c, e affords the cyclic hydroxamic acids 9a-c that can be reduced by titanium chloride to 8. Addition of phenyl isocyanate to 9a gives smoothly 10 and compound 11 arises from alkylat ion of 9b with tert-butyl bromoacetate.