Synthesis and spectroscopic analysis of acyclic C-nucleosides and homo-C-analogues from 1-(chloroalkyl)-1-aza-2-azoniaallene salts

Treatment of alpha,alpha'-dichloroazo compounds 1 with SbCl5 afforded the 1 -(chloroalkyl)-1-aza-2-azoniaallene salts (2) which reacted in a 1,3-dipola r cycloaddition with the acetoxy nitriles 3 and 4 to the 1,2,4-triazolium s alts 5 and 6, respectively. 5 and 6 rearranged spontaneously to the protona ted 1,2,4 triazoles 7 and 8, respectively. The salts 7 were in situ hydroly zed to the acyclic 1,2,4-triazole C-nucleosides 9 which gave the free nucle osides 11a,b, and f after deblocking. Treatment of 8 with NaOMe resulted in the de-acetylation along with the hydrolysis of the salts to the free homo nucleosides 13a-f. (C) 1998 Elsevier Science Ltd. All rights reserved.