D. P. Green, T. Ravindranathan, C. Reese
1970
Citations
1
Influential Citations
21
Citations
Journal
Tetrahedron
Abstract
Abstract The conversion of N4-benzoylcytidine, N4-anisoylcytidine, N2-benzoylguanosine and inosine into their 3′-acetates, and N6,N6-dimethyladenosine into its 3′-benzoate by the orthoester exchange method, are described. All these 3′-O-acyl derivatives (IX) were obtained crystalline and in good or satisfactory yields. 2′-O-Acetyl-N4-anisoylcytidine (XIIIb) and 2′-O-benzoyl-N6,N6-dimethyladenosine (XVII) were also obtained crystalline. The above 3′-O-acyl derivatives, and also 3′-O-acetyl-uridine and -adenosine, were treated with 4-methoxy-5,6-dihydro-2H-pyran (X) in the presence of acid to give the corresponding 3′-O-acyl ribonucleoside 2′,5′-bisketals (XI) in good yields. Treatment of the latter with base gave the desired ribonucleoside 2′,5′-bisketals (V). Some of the bisketal esters (XI) and most of the bisketals (V) were isolated as pure crystalline solids. Treatment of the uridine 2′,5′-bisketal (V; B = uracil-1) with aqueous acid under controlled conditions revealed that its 5′-ketal function was ca. twice as labile to acidic hydrolysis as its 2′-ketal function.