The Mitsunobu reaction in preparing 3-deazapurine carbocyclic nucleosides

The coupling reaction of 4-chloro-1H-imidazo4,5-c]pyridine (6-chloro-3-deazapurine, 3) with several cyclopentyl derivatives under Mitsunubo reaction conditions provides an efficient entry into N-7 and N-9 substituted 3-deazapurine carbocyclic nucleosides of antiviral potential. The versatility of this procedure is illustrated with a new and efficient synthesis of (−)-3-deazaaristeromycin, a formal preparation of 3-deazaneplanocin A, and a route to 3-deaza-5′-homoaristeromycin.