84224-65-7Relevant articles and documents
Highly diastereoselective α-mannopyranosylation in the absence of participating protecting groups
Crich, David,Cai, Weiling,Dai, Zongmin
, p. 1291 - 1297 (2007/10/03)
S-Phenyl 2,6-di-O-benzyl-3,4-O-(2',3'-dimethoxybutane-2',3'-diyl)- 1- thia-α-D-mannopyranoside and its sulfoxide, following activation at -78 °C with benzenesulfenyl triflate or trifiic anhydride, respectively, provide the corresponding α-mannosyl triflate as demonstrated by NMR spectroscopy. On addition of an acceptor alcohol α-mannosides are then formed. Similarly, S- phenyl 2,3-O-carbonyl-4,6-O-benzylidene-1-thia-α-D-mannopyranoside and ethyl 3-O-benzoyl-4,6-O-benzylidene-2-O-(tert-butyldimethylsilyl)-1-thia-α-D- mannopyranoside both provide α-mannosides on activation with benzenesulfenyl triflate followed by addition of an alcohol. These results stand in direct contrast to the highly β-selective couplings of comparable glycosylations with 2,3-di-O-benzyl-4,6-O-benzylidene protected mannosyl donors and draw attention to the subtle interplay of reactivity and structure in carbohydrate chemistry.
Synthesis and Reactions of Sulfenic Trifluoromethanesulfonic Anhydrides
Effenberger, Franz,Russ, Werner
, p. 3719 - 3736 (2007/10/02)
Sulfenyl halogenides 1 and 4 react with silver trifluoromethanesulfonate (2) to give aryl 3 and alkylsulfenic trifluoromethanesulfonic anhydrides 5, resp., in good yields; 3 and 5 could not be isolated because of their instability. 1H NMR spectroscopic data of 5a, b, each in dichloromethane and nitromethane, resp., are indicative of a dissoziation to adducts of alkylsulfenylium ions and the solvent.Whereas 3 do not react with aromatic compounds, addition products with diphenylacetylene, arylsulfenylvinyl trifluoromethanesulfonates 11, are formed smoothly, which under the reaction conditions immediately cyclize to give benzothiophenes 10 in excellent yields.