Synthesis of Novel Anellated Pyranosides as Precursors of C‐Nucleoside Analogues Using Isopropyl 6‐O‐Acetyl‐3‐deoxy‐4‐S‐ethyl‐4‐thio‐α‐D‐threo‐hexopyranosid‐2‐ulose

Abstract

Isopropyl 6‐O‐acetyl‐3‐deoxy‐4‐S‐ethyl‐4‐thio‐α‐D‐threo‐hexopyranosid‐2‐ulose (3) was converted to the corresponding 3‐[bis(methylthio)methylene] derivative 4 with a push–pull activated C–C double bond. Treatment of 4 with hydrazine and methylhydrazine afforded the pyrano[3,4‐c]pyrazol‐5‐ylmethyl acetates 5a and 5b, respectively. Desulfurization of compound 4 with sodium boron hydride yielded the 3‐[(methylthio)methylene]hexopyranosid‐2‐ulose 7. Compound 7 was reacted with amines to furnish 3‐aminomethylene‐hexopyranosid‐2‐uloses 8, 9. Reaction of 7 with hydrazine hydrate, hydrazines, hydroxylamine, and benzamidine afforded the pyrazolo, isoxazalo, and pyrimido anellated pyranosides (10–13).

^#Dedicated to Professor Dr. Günther Oehme on the occasion of his 65th birthday.

Keywords:

• Deoxyuloses
• Thiosugars
• Branched sugars
• Push–pull alkenes
• Heteroanellated pyranosides

Acknowledgments

J. Q. is grateful to the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP, Brasil) and the Deutscher Akademischer Austauschdienst for financial support. R. M. would like to thank the Deutscher Akademischer Austauschdienst for a scholarship.

We are grateful to the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie for financial support.

Notes

^#Dedicated to Professor Dr. Günther Oehme on the occasion of his 65th birthday.