77668-06-5Relevant academic research and scientific papers
Nucleosides. 117. Synthesis of 4-Oxo-8-(β-D-ribofuranosyl)-3H-pyrazolo-1,3,5-triazine (OPTR) via 3-Amino-2N-carbamoyl-4-(β-D-ribofuranosyl)pyrazole (ACPR) Derivatives
Chu, C. K.,Watanabe, K. A.,Fox, J. J.
, p. 1435 - 1439 (2007/10/02)
Reaction of 2-formyl-2-(2,3-O-isoprpylidene-5-O-trityl-D-ribofuranosyl)acetonotrile (VII) with semicarbazide hydrochloride followed by sodium ethoxide treatment afforded α,β-mixture of 3-amino-2N-carbamoyl-4-(2,3-O-isopropylidene-5-O-trityl-D-ribofuranosyl)pyrazole (IX).Conversion of IX to 4-oxo-8-(2,3-O-isopropylidene-5-O-trityl-D-ribofuranosyl)-3H-pyrazolo-1,3,5-triazine (XIII) was achieved by treatment of IX with ethylorthoformate.The β-isomer IXb gave only β-isomer XIIIb, and the α-isomer was converted exclusively into the α-isomer XIIIa.Upon deprotection with 3percent n-butanolic hydrogen chloride, both IXa and IXb gave the same mixture of the α- and β-isomers of 3-amino-2N-carbamoyl-4-(D-ribosyl)pyrazole, which were separated by chromatography. The syntheses of the hitherto unknown compounds, 3-amino-2N-carbamoylpyrazole (IVa) and its 4-methyl analog (IVb) are also reported.Experimental details of the synthesis of 3-amino-4-(2,3-O-isopropylidene-5-O-trityl-β-D-ribofuranosyl)pyrazole (XIIb), an important intermediate for "purine-like" C-nucleosides, are also described.
