A New Oxidative Conversion of Carbohydrate Benzyl Ethers to Benzoyl Esters with RuCl₃-NaIO

Total Synthesis ofN-Malayamycin A and Related Bicyclic Purine and Pyrimidine Nucleosides

“…To secure a 1‘,2‘- trans relationship of the intended nucleosides, we relied on a neighboring group participation by the C 2 ‘-benzoate. Thus, treatment of 17 with RuCl 3 /NaIO 4 gave the desired benzoate 18 in 80% yield. The diphenyldithioacetal 19 was easily obtained from 18 by treatment with benzene thiol and BF 3 ·Et 2 O .…”

Nonpyrogenic Molecular Adjuvants Based on norAbu-Muramyldipeptide and norAbu-Glucosaminyl Muramyldipeptide: Synthesis, Molecular Mechanisms of Action, and Biological Activities in Vitro and in Vivo

“…Generally, the allyl group was first isomerized to become a propenyl group, using Wilkinson’s catalyst [RhCl­(PPh 3 ) 3 ], then subject to acid catalyzed cleavage, leaving the opportunity for attachment of a glycoloyl moiety by simple alkylation. ,,, All three steps could be conflated to one by conversion of the allyl group to a glycoloyl ether moiety by the action of RuO 4 that can be generated in situ by catalytic amount of RuCl 3 using NaIO 4 as an oxidant under controlled conditions (Schemes and ) . Bearing in mind that RuO 4 is very powerful oxidizing agent reaction conditions were carefully adjusted for selective allyl group release in the presence of other protecting groups …”

“…Initially, allyl derivative 1 was subject to benzylation to give benzyl 2-acetamido-3- O -allyl-4,6-di- O -benzyl-2-deoxy-α- d -glucopyranoside 2 by treatment with benzyl bromide and sodium hydride in DMF according to published procedure. ,,, Glucopyranoside 2 was then treated with NaIO 4 and RuCl 3 in CCl 4 –MeCN–H 2 O at 0 °C (Scheme ). In early trial runs with these reactions conditions, a range of reaction products were observed being diol 3 , aldehyde 4 , cyclic byproduct 5 , and the desired protected normuramic acid 6 intermediate. The formation of undesired cyclic byproduct 5 was suppressed, and direct formation of carboxyl function was facilitated by carrying out the oxidation at moderate temperatures in the presence of an excess of NaIO 4 , thereby giving the protected normuramic acid 6 intermediate in high overall yield.…”

“…N -2,2,2-Trichloroethoxycarbonyl (Troc) derivative 11 was prepared by reaction of amine 9 with trichloroethoxycarbonyl chloride in pyridine. Thereafter, 10 and 11 were used to prepare intermediate glucosaminyl normuramic acid building blocks 12 and 13 (Scheme ), then converted to their respective methyl esters 14 and 15 by reaction with diazomethane in order to allow complete characterization of these compounds.…”