78880-58-7Relevant articles and documents
Reengineering Chemical Glycosylation: Direct, Metal-Free Anomeric O-Arylation of Unactivated Carbohydrates
Lucchetti, Nicola,Gilmour, Ryan
, p. 16266 - 16270 (2018/10/24)
To sustain innovation in glycobiology, effective routes to well-defined carbohydrate probes must be developed. For over a century, glycosylation has been dominated by the formation of the anomeric Csp3?O acetal junction in glycostructures. A dissociative mechanistic spectrum spanning SN1 and SN2 is frequently operational thereby reducing the efficiency. By reengineering this fundamental process, an orthogonal disconnection allows the acetal to be formed directly from the reducing sugar without the need for substrate pre-functionalisation. The use of stable aryliodonium salts facilitates a formal O?H functionalisation reaction. This allows lactols to undergo mild, metal-free O-arylation at ambient temperature. The efficiency of the transformation has been validated using a variety of pyranoside and furanoside monosaccharides in addition to biologically relevant di- and trisaccharides (up to 85 %). Fluorinated mechanistic probes that augment the anomeric effect were employed. It is envisaged that this strategy will prove expansive for the construction of complex acetals under substrate-based stereocontrol.
A stable, commercially available sulfenyl chloride for the activation of thioglycosides in conjunction with silver trifluoromethanesulfonate
Crich, David,Cai, Feng,Yang, Fan
, p. 1858 - 1862 (2008/12/22)
p-Nitrobenzenesulfenyl chloride is a stable commercially available sulfenyl chloride that, in conjunction with silver triflate, cleanly activates a wide range of thioglycosides for glycosylation at -78 °C in CH2Cl2.
Direct chemical synthesis of β-mannopyranosides and other glycosides via glycosyl triflates
Crich, David,Sun, Sanxing
, p. 8321 - 8348 (2007/10/03)
High yield, highly stereoselective methods for the synthesis of β- mannopyranosides primary, secondary, and tertiary alcohols are presented. Activation of mannosyl sulfoxides or mannosyl thioglycosides with trifluoromethanesulfonic anhydride or benzenesulfenyl triflate, respectively, leads to the efficient formation of α-mannosyl triflates at -78 °C in dichloromethane, in the presence of 2,6-di-tertbutyl-4-methylpyridine. These triflates then react S(N)2-like with alcohols to give the β-mannosides. The use of a 4,6-O-benzylidene protected mannose is required for high selectivity, as is the use of non-participating protecting groups on O-2 and O-3 of the donors. It is further demonstrated that the thioglycoside/benzensulfenyl triflate activation is applicable in the glucoside series, when both armed and disarmed protecting groups are tolerated.