Synthesis of 4(5)-(5'-amino-5'-deoxy-α-L-arabino-furanosyl)imidazole and its 5'-derivatives using modified Mitsunobu cyclization: Synthetic studies toward novel histamine H3-ligands

Article abstract of DOI:10.3987/com-00-8956

The modified Mitsunobu cyclization of 4-(2',3',5'-tri-O-benzyl-L-arabinosyl)imidazole (11RS) using N,N,N',N'-tetramethylazodicarboxamide and Bu₃P followed by ethoxycarbonylation produced a mixture (α / β = 20 / 1) of ethyl 4-(2',3',5'-tri-O-benzyl-L-arabinofuranosyl)-imidazole-1-carboxylate (13). The compound (13) was converted into ethyl 4-(5'-deoxy-5'-phthaloylamino-L-arabinofuranosyl)imidazole-1-carboxylate (15), which was subsequently led to 4-(5'-amino-5'-deoxy-α-L-arabinofuranosyl)imidazole (2α). The 4(5)-{5-[N-(4-chlorophenyl)thio-ureido]-α-L-arabinofuranosyl}imidazole (18), 4(5)-{5-[N-(4-chlorophenyl)-ureido]-α-L-arabinofuranosyl}imidazole (19), and 1-cyano-2-methyl-3-{5-deoxy-1-[1H-imidazol-4(5)-yl]-α-L-arabinofuranosyl}g uanidine (20) were efficiently synthesized from 2α.