80956-03-2Relevant academic research and scientific papers
Trityl Derivatives of Cellobiose. V. Selective Acetylation of 6- and 6'-Mono-O-tritylcellobiose and Their Methyl β-Glycosides
Koizumi, Kyoko,Utamura, Toshiko
, p. 2785 - 2790 (2007/10/02)
The selective acetylation of 6'-O-tritylcellobiose (1), 6-O-tritylcellobiose (3), and their methyl β-glycosides (2 and 4) with 6 molar equivalents of acetyl chloride in pyridine-toluene at 1-4 deg C has been studied.Acetylation of 1 gave the 1,2,6,2',3',4'-hexaacetate (1A) and 1,2,6,2',3'-pentaacetate (1B), and that of 3 gave the peracetate, 1,2,2',3',4',6'-hexaacetate (3A), and 1,2,3,3',4',6'-hexaacetate (3B).On the basis of the yields of partially acetylated products from 2, i.e., 2,6,2',3',4'-pentaacetate (2A, 15.5percent), 2,6,2',3'-tetraacetate (2B, 16.2percent), 2,6,3',4'-tetraacetate (2C, 10.8percent), 6,2',3',4'-tetraacetate (2D, ca. 10.6percent), 6,2',3'-triacetate (2E, 7.9percent), 2,6,3'-triacetate (2F, ca. 10.5percent), and 3,6,2',3'-tetraacetate (2F', ca. 6.9percent), it was deduced that the order of reactivities of the secondary hydroxyl groups in 2 is 3'>2' ca. 2>4'>>3.The partially acetylated products from 4 were separated by column chromatography and semipreparative HPLC to afford the peracetate (17.7percent), 2,2',3',4',6'-pentaacetate (4A, 11.1percent), 2,3,3',4',6'-pentaacetate (4B, 26.0percent), and 2,3,2',3',6'-pentaacetate (4C, 6.5percent).It seems likely that the order of reactivities of the secondary hydroxyl groups in 4 toward acetyl chloride is 2,3'>4'>3>2'.These results suggested that TrO-6' interacts sterically with HO-3 and HO-4', while TrO-6 affects only HO-2'.Keywords-selective acetylation; partially acetylated 6-O-tritylcellobioses; partially acetylated 6'-O-tritylcellobioses; partially acetylated methyl 6-O-trityl-β-cellobiosides; partially acetylated methyl 6'-O-trityl-β-cellobiosides; column chromatography; semi-preparative HPLC; recycle chromatography; 1H-NMR; Rf on TLC
