The cyclization of 8-carboxamido-2′-O-tosyladenosine. A new preparation of 9-β-D-arabinofuranosyladenine (ara-A)
Abstract
In alkaline solution, 8-carboxamido-2′-O-tosyladenosine (4e; R2= R3= H), which may be prepared from adenosine in 7 steps, readily cyclizes to give (5); in neutral or weakly basic solution, it undergoes virtually quantitative conversion into ara-A (1a).