Chemoselective and Practical Deprotection of Alkyl Trialkylsilyl Ethers in the Presence of Aryl Trialkylsilyl Ethers by a Catalytic Amount of Sc(OTf)₃

Abstract

Treatment of alkyl trialkylsilyl ethers with 0.5 mol% of Sc(OTf) 3 combined with 5 equivalents of water in acetonitrile provides an efficient and practical method for the deprotection of silyl ethers. Alcoholic trialkylsilyl ethers have been cleaved selectively in the presence of phenolic trialkylsilyl ethers.

Assembly of a Series of Malarial Glycosylphosphatidylinositol Anchor Oligosaccharides

“…Alcohol 33 was phosphitylated by treatment with H‐phosphonate 17 and pivaloyl chloride before oxidation with wet iodine provided the phosphodiester 36 in 95 % yield. The TIPS group masking the primary C6 hydroxyl of the terminal mannose of 36 was removed using Sc(OTf) 3 in wet acetonitrile at 50 °C to afford alcohol 38 in 76 % yield 31. To introduce the second phosphate ester 38 was treated with H‐phosphonate 40 12 and pivaloyl chloride, again followed by oxidation with wet iodine to furnish 41 .…”

Synthesis and Biological Evaluation of Apicularen A Analogues

“…[23] Complete silylation gave the disilyl ether 15, and subsequently the primary silyl ether was cleaved with catalytic amounts of scandium(iii) triflate in wet acetonitrile. [24] Oxidation of the primary alcohol 16 with NMO in the presence of TPAP provided the aldehyde 17, and the hemiaminal 19 was prepared by treatment of the aldehyde 17 with the anion of the hep-tadienamide [15] 18. The hemiaminal was formed as a 1:1 mixture of diastereomers, and elimination of water to afford the desired enamides could be achieved by stirring the hemiaminals with acetic anhydride and pyridine, first at room temperature and then at reflux.…”

Efficient and versatile synthesis of 5-O-acylquinic acids with a direct esterification using a p-methoxybenzyl quinate as a key intermediate

“…However, desilylation of 8 by TBAF produced PMB quinate 4 in modest yield (55%) ( Table 1, entry 1). A Sc(OTf) 3 -catalyzed desilylation 23 increased the yield (73%) ( Table 1, entry 2). Finally, TBAF/AcOH gave 4 in 96% yield 24 (79% overall yield from 6) ( Table 1, entry 3); its structure was unambiguously proven by X-ray crystallographic analysis (Fig.…”