Some pyrazolo[3,4&lquinoxalines have tuberculostatic activity in vitro [31, while others show antifungal activity [4]. We have been interested recently in the synthesis of C-nucleoside analogues having the pyrazolo[3,4-blquinoxaline base moiety and their substituted analogues [2,5-71 for biological evaluation. These cyclic compounds are obtained by acid-catalyzed dehydration of their acyclic precursors, usually as anomeric mixtures, and the determination of the anomeric configuration is a problem of special importance. High-resolution NMR and CD spectra [51 have been used for this purpose. The previously studied analogues were prepared by dehydrative cyclization of acyclic precursors having the same Darubino-polyhydroxyalkyl side chain, but with different substituents at the base moiety. Acid-catalyzed dehydration of these compounds gives predominantly the p-anomeric C-nucleoside. In this work, a stereoisomeric pyrazolo[3,4-blquinoxaline analogue having the 1~x0 configuration of the side chain was prepared, and the cyclized C-nucleoside products were isolated and their anomeric configurations determined by 'H NMR and CD spectroscopy. * For a preliminary report see Ref 1. C-Nucleoside Pyrazolo[3,4-blquinoxaline Analogues Part V. For Part IV, see Ref. 2. ** Dedicated to Professor Leroy B. Townsend on the occasion of his 60th birthday. ' Deceased 1992.