Nucleosides acetolysis

A nucleoside derivative of 4-acetamido-4-deoxy-D-xyIofuranose was synthesized by a series of reactions. Partial benzoylation of methyl )8-L-arabinopyranoside produces " methyl 2,3-di-0-benzoyl-j3-L-arabinopyranoside. p-Toluenesulfonylation at 0-4, followed by displacement with sodium azide, gives methyl 4-azido-2,3-di-0-benzoyl-4-deoxy-a-D-xylopyranoside. Hydrogenation, debenzoylation, N-acetylation, and acetolysis yield 4-acetamido-l,2,3,5-tetra-0-acetyl-4-deoxy-D-xylofuranose (D-enantiomorph of 191), which reacts in the presence of titanium tetrachloride in chloroform with chloromercuri-(6-benzoyladenine), giving, after deacylation, 9-(4-acetamido-4-deoxy-)8-D-xylofuranosyl)adenine. ... 

For synthesis of nucleosides, methyl 4-acetamido-2,3-di-0-benzoyl-4-deoxy-a-D-ribopyranoside (198c), obtained from 198a, was trans-formed by acetolysis into 4-acetamido-l,5-di-0-acetyl-2,3-di-0-benzoyl-4-deoxy-D-ribofuranose (199b). Either with preliminary treatment with hydrogen chloride in acetyl chloride, or directly, in the presence of titanium tetrachloride, 199b gave with chloromercuri-(6-... 

When 180 was subjected to acetolysis it gave an acyclic derivative, which when submitted to nucleosidation gave the acyclic nucleoside 181 (90-JOC3772). However, reaction of methyl-2-3,S-tri-O-benzoyl-a-o-arabino-side with silylated pyrimidines in the presence of TMS triflate gave the acyclic nucleoside 183 in addition to 182 (92S1299). 

Acetolysis of the anhydrosugar 118 gave a mixture of pyranosyl and furanosyl glycosyl acetates, which could be converted to the 3 -hydroxymethyl nucleosides 119 and, after a deacetylation-periodate-borohydride sequence, 120 respectively. ... 

Acetolysis of the hex-5-enopyranoside (81) and condensation of the product with 6-benzamido(chloromercuri)purine gave the unsaturated nucleosides (82) and (83) after removal of the blocking groups. The D-r/i < -nucleoside (82), which was the major product, was selectively destroyed with periodate to facilitate isolation of (83). The a-L-isomer of (83) was prepared by the same route and also by an improved method starting from D-galactose... 

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