Glycosidation Boron trifluoride etherate

Prandi, J, Audin, C, Beau, J M, Synthesis of C-glycosides boron trifluoride etherate-promoted opening of epoxides by anomeric anions. Tetrahedron Lett., 32, 769-772, 1991. 

It was projected that compound 13 could be stereoselectively linked, through its free phenolic hydroxyl group, with the anomeric carbon of intermediate 12 under suitably acidic conditions (see Scheme 8). Gratifyingly, the action of boron trifluoride etherate on a mixture of 12 and 13 in CH2CI2 at -50 °C induces a completely stereoselective glycosidation reaction, providing the desired a-ano-mer 48 in an excellent yield of 95 % from 46. It is presumed that boron trifluoride initiates cleavage of the anomeric trichloroacetimi-... 

Glycosidation Allyl chloroformate, 9 Boron trifluoride etherate, 43 Silver(I) tetrafluoroborate, 273 Silver (I) trifluoromethanesulfonate, 274 Thallium zeolites, 296 Tin(II) trifluoromethanesulfonate, 301 Trichloroacetonitrile, 321 Grignard reactions and reactions of... 

Heyns et al. [53] started with di-O-acetyl-L-rhamnal (28) which after reaction with sodium azide in the presence of boron trifluoride etherate as Lewis catalyst gave again the four products 79-82 (R=Ac). Subsequent quenching with NIS and the aglycone led to ristosamine and acosamine glycosides 86 and 87. 

Glycosides of unprotected D-glycuronic acids have been formed directly in the appropriate alcohol with boron trifluoride etherate as catalyst, affording D-glycosiduronates.246 D-Glucosyluronic acid trichloroacetimidate has also been used for glycosylation of uronic acids.247... 

The synthetic plan in Figure 6 has been realized as full steps shown in Figure 7. C-Glycosidation of 18 with phenylthiotrimethylsilyl-acetylene and boron trifluoride etherate followed by treatment with biscobaltoctacarbonyl gave the biscobalthexacarbonyl complex 25 in 92% yield. Epimerization of the cobalt complex 25 was achieved with trifluoromethane sulfonic acid in... 

Boron trifluoride etherate [615-617] and SnCU [618,619] are the catalysts that are traditionally used in this reaction. Recently described promoters include IDCP [620,621], DDQ [622], montmorillonite K-10 [623], h [624], FeCls [625], InCls [626,627], Sc(OXf)3 [628], the l2-thiolacetic acid system [155], Yb(OTf)3 [629], and TMSOTf [630]. The 2,3-unsaturated glycosides produced in these reactions can easily be converted into the 2,3-dideoxy derivatives or to a variety of other products by functionalization of the double bond. 

Dahmen, J, Frejd, T, Magnusson, G, Noori, G, Boron trifluoride etherate-induced glycosidation formation of alkyl glycosides and thioglycosides of 2-deoxy-2-phthalimidoglycopyranoses, Carbohydr. Res., 114, 328-330, 1983. 

The reaction of the tetra-O-acetyl-5-thio-a-D-xylopyranosyl-l-O-trichloroacetimidate with phenol in the presence of boron trifluoride-etherate, at low temperatures, gives a mixture of the corresponding 0-glycosidation and the electrophilic substitution product, 4-hydroxyphenyl-5-thio-D-xylopyranoside (equation 6). ... 

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