NUCLEOSIDES AND NUCLEOTIDES .143. SYNTHESIS OF 5-AMINO-4-IMIDAZOLECARBOXAMIDE (AICA) DEOXYRIBOSIDES FROM DEOXYINOSINES AND THEIR CONVERSIONINTO 3-DEAZAPURINE DERIVATIVES

An efficient and large scale chemical synthesis of 5-aminoimidazole-4- carboxamide (AICA) 2'-deoxyriboside (5a) and its 3'-deoxyriboside 5b i s described. Treatment of 5'-di-O-acetyl-N-1-triphenylmethyl-2'-deoxyi nosine (3a) with 5 N NaOH in EtOH, followed by anhydrous trifluoroacet ic acid gave 5a in 59% yield from 2'-deoxyinosine (1a). AICA 3'-deoxyr iboside (5b) was also obtained in a similar manner as for 5a in 73% yi eld from 3'-deoxyinosine (1b). Conversion of these AICA derivatives (5 a, b) into 3-deazapurine derivatives (9a, b, 15a, b, 20a, b) is also d escribed.