Titanium Tetrachloride in Chloroform

It is noteworthy that all attempts to convert 275 into the corresponding D-glucosyl bromide with hydrogen bromide in acetic acid were unsuccessful, because the reagent was also attached to the 2-(thiocyanato) group. Treatment of 275 with titanium tetrachloride in chloroform afforded crystalline 3,4,6-tri-0-acetyl-2-deoxy-2-(thiocyanato)-a-D-glucosyl chloride (277)... 

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. ... 

Conversion of either pentaacetate to crystalline acetochloro-o-n-altrose was effected in good yield by the action of titanium tetrachloride in chloroform solution. Replacement of the chlorine atom by a hydroxyl group was accomplished by shaking the acetochloro compound with silver carbonate and aqueous acetone. The resulting tetraacetate appeared as the /3-modification, mutarotating from [ajo —6.0 to - -12.9° in chloroform solution. 

Treatment of Y -(benzylidene)benzohydrazonoyl chlorides 38 with titanium tetrachloride in chloroform produced symmetrically substituted 3,6-diaryl-l,4-dihydro-l,2,4,5-tetrazines 2 in moderate yields. The authors suggest that cyclocondensation between two molecules of hydrazonoyl chloride takes place first, followed by elimination of two molecules of an aldehyde during hydrolytic workup. Oxidation of the dihydrotetrazines 2 with nitrous acid afforded the fully conjugated tetrazines 1 in 32-56% yields (Scheme 8) <2000MI37>. 

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