First Synthesis of Double Headed 1,2,4-Triazino[5,6-b]indole AcycloC-Nucleosides

Abstract

Heterocyclization of bis(2-oxo-indol-3-ylidene)-galactaric acid hydrazide (3) with a variety of one-nitrogen cyclizing agents gave the corresponding 1,4-bis{1,2,4-triazino[5,6-b]indol-3-yl}-galacto-tetritols 4-8. Acetylation of the latter double headed acyclo C-nucleosides with acetic anhydride in the presence of pyridine at ambient temperature resulted in N- and O-acetylation to give the corresponding 1,2,3,4-tetra-O-acetyl-1,4-bis{1,2,4-triazino[5,6-b]indol-3-yl}-galacto-tetritols 9-13 which were found to exist in centro-symmetric zigzag conformations 20. The assigned structures were corroborated by 1 H, 1 3 C NMR as well as mass spectra.