128142-70-1Relevant articles and documents
Deprotection of silyl ethers by using SO3H silica gel: Application to sugar, nucleoside, and alkaloid derivatives
Fujii, Hideaki,Shimada, Naoyuki,Ohtawa, Masaki,Karaki, Fumika,Koshizuka, Masayoshi,Hayashida, Kohei,Kamimura, Mitsuhiro,Makino, Kazuishi,Nagamitsu, Tohru,Nagase, Hiroshi
, p. 5425 - 5429 (2017/08/11)
We applied a desilylation procedure using SO3H silica gel, with the surface modified by alkylsulfonic acid groups, to silylated sugar, nucleoside, and alkaloid derivatives. The treatment with SO3H silica gel provided desilylated products in good to excellent yield. In the reactions of sugar and nucleoside derivatives, no silyl residue was detected in the crude products, but the crude products of the reaction of alkaloids contained small amounts of silyl residues. Even though the sugar and nucleoside derivatives had a labile glycosyl and C–N bond, respectively, these bonds tolerated the reaction conditions. These outcomes suggested that the desilylation procedure using SO3H silica gel would be applicable to the deprotection of a variety of types of compounds protected by silyl groups. In a gram scale experiment, the desilylation procedure successfully proceeded without the observation of any silyl residue in the crude product.
Highly stereoselective β-mannopyranosylation via the 1-α-glycosyloxy-isochromenylium-4-gold(I) intermediates
Zhu, Yugen,Yu, Biao
supporting information, p. 8771 - 8780 (2015/06/08)
While the gold(I)-catalyzed glycosylation reaction with 4,6-O-benzylidene tethered mannosyl ortho-alkynylbenzoates as donors falls squarely into the category of the Crich-type β-selective mannosylation when Ph3PAuOTf is used as the catalyst, in that the mannosyl α-triflates are invoked, replacement of the -OTf in the gold(I) complex with less nucleophilic counter anions (i.e., -NTf2, -SbF6, -BF4, and -BAr4F) leads to complete loss of β-selectivity with the mannosyl ortho-alkynylbenzoate β-donors. Nevertheless, with the α-donors, the mannosylation reactions under the catalysis of Ph3PAuBAr4F (BAr4F=tetrakis[3,5-bis(trifluoromethyl)phenyl]borate) are especially highly β-selective and accommodate a broad scope of substrates; these include glycosylation with mannosyl donors installed with a bulky TBS group at O3, donors bearing 4,6-di-O-benzoyl groups, and acceptors known as sterically unmatched or hindered. For the ortho-alkynylbenzoate β-donors, an anomerization and glycosylation sequence can also ensure the highly β-selective mannosylation. The 1-α-mannosyloxy-isochromenylium-4-gold(I) complex (Cα), readily generated upon activation of the α-mannosyl ortho-alkynylbenzoate (1 α) with Ph3PAuBAr4F at -35 C, was well characterized by NMR spectroscopy; the occurrence of this species accounts for the high β-selectivity in the present mannosylation.
Synthesis of a Methyl Heptaglucoside: Analogue of the Phytoalexin Elicitor from Phytophtora Megasperma
Verduyn, R.,Douwes, M.,Klein, P.A.M. van der,Moesinger, E.M.,Marel, G.A. van der,Boom, J.H. van
, p. 7301 - 7316 (2007/10/02)
The ethylthio-laminaribioside 29, prepared by regiospecific glycosylation of ethyl 4,6-O-benzylidene-1-thio-β-D-glucopyranoside (9) with 2,3,4,6-tetra-O-benzoyl-D-glucopyranosyl imidate 17 and subsequent benzoylation, could be elongated in a step-wise fas
