CHEMICAL SYNTHESIS OF 2-, 3- AND 4-TRIPHENYLMETHYL ETHERS OF METHYL (METHYL- α - D -MANNOPYRANOSID )URONATE DERIVATIVES
V. I. BETANELI, O. V. BRUKHANOVA, A. Ya. OTT, N. K. KOCHETKOV
N. D. Zelinsky Institute of Organic Chemistry, Academy of Sciences of the USSR, Moscow
Abstract: A directed chemical synthesis of 2-, 3- and 4-trityl ethers of methyl (methyl-α-D-mannopyranosid)uronate is performed. An efficient procedure to prepare methyl (met-hyl- α-D--mannopyranosid)uronate from methyl- α-D--mannopyranoside (53% for 6 steps) is suggested. An unpredictable regioselective tritylation of a, e-diol — methyl (methyl-4-O-acetyl- α-D--mannopyranosid)uronate — was found, the preparative yield of the axial trityloxy isomer being 65%. Acetylation of the diol, as could be expected, proceeds selectively at the equatorial hydroxyl group. The reaction of triol — methyl (methyl-α-D-mannopyranosid)uronate — with trimethylorthoacetate smoothly leads to the orthoester — 2,3-O-(l-methoxy)ethylidene derivative. Acetylation of the orthoester followed by the hydrolytical ring opening of the cyclic orthoester function and tritylation afforded 3-trityl ether (64% for 4 steps). 4-Trityl ether was obtained (68% for 4 steps) by tritylation of bicyclic orthoester followed by subsequent hydrolytical ring opening of the orthoester function, practically with no splitting of O-triphenylmethyl one, and acetylation.
Russian Journal of Bioorganic Chemistry 1990, 16 (3):390-401