A CONVENIENT SYNTHESIS OF 5-SUBSTITUTED-4-HYDROXY-3,4,5,6-TETRAHYDRO-2H-PYRAN-2-ONES VIA A CHEMOSELECTIVE DIFFERENTIATION OF THE TWO ESTER FUNCTIONS OF DIMETHYL ACETONEDICARBOXYLATE

Article abstract of DOI:10.1016/0040-4039(88)80010-8

Dimethyl acetonedicarboxylate formed the enamine 1 with benzylamine and thereby converted one of the carbomethoxy groups into a less electrophilic vinylogous urethane.Subsequent sequential alkylation of the active methylene moiety, chemoselective NaBH4 reduction of the ester function, hydrolysis of the enamine moiety and reduction of the newly generated keto group afforded alcohols 5.Hydrolysis of the ester and lactonization gave the readily separable cis and trans lactones 8 and 9.