An Approach toC-Branched and Heterocyclic Anellated Pyranosides by Reaction ofα-D-erythro-Hexopyranosid-2-ulose with Orthoformic Acid Derivatives

Abstract

The push-pull functionalization of the ulose 1 to give the (E)-configurated dimethylaminomethylene pyranosidulose 2 was achieved with bis(dimethylamino)tert-butoxymethane. Substitution of the dimethylamino group by different amines provided the corresponding sugar enamines 3 as (Z) isomers. 2 reacted with hydrazine hydrate to furnish the pyrano[3,4-c]pyrazole 4. Treatment of 2 with acetamidine hydrochloride, benzamidine hydrochloride, S-methylisothiouronium methylsulfate and guanidine carbonate, respectively, in the presence of bases yielded the pyrimidoanellated pyranosides 5. Reaction of 2, ethyl 2-cyano-acetimidate hydrochloride 7 and sodium hydride afforded a mixture of a pyrido- and pyranoanellated pyranoside 9 and 10, respectively.