Nucleosides and Nucleotides.Part 207:Studies in the Chemical Conversion of the 4-Carboxamide Group of 5-Amino-1-#beta#-D-ribofuranosylimidazole-4-carboxamide (AICA-Riboside).Application for the Synthesis of 1-Deazaguanosine

摘要

A mild and versatile chemical conversion of the 4-carboxamide group of 5-amino-1-#beta#-D-ribofuranosylimidazole-4-carboxamide (AICA-riboside) is described.The reaction of protected AICA-riboside with di-tert-butyl dicarbonate gave 5-[N,N-di-(tert-butoxycarbonyl)]-amino-1-(5-O-tert-butyldimethylsilyl-2.3-O-isopropylidne-#beta#-D-ribofuranosyl)imidazole-4-[N,N-di(tert-butoxycarbonyl)]carboxamide in 71% yield.The resulting tetraBoc derivative was treated with sodium methoxide,benzylamine,or acetonitrile anion to give the corresponding methyl ester,N-benzylcarboxamide,or cyanoacetyl products.The 4-cyanoacetylimidazole derivative was converted into 1-deazaguanosine via an intramolecular cyclization.