A-D-Glucopyranosyl chloride

The Mukaiyama condensation method was also utilized in the synthesis of several antibiotics and related bioactive substances. These syntheses include apramycin, using 4-azido-2,3,6-tri-(P-benzyl-4-deoxy-) -D-glucopyranosyl fluoride (prepared from the corresponding a-D-glucopyranosyl chloride by the AgF method ) avermectin B , using protected sugar derivatives of oleandrosyl fluoride (a-L-Ole-F) and 0-(a-L-01e)-(1 4)-a-L-0le-F (both... 

Similarly, Shen and coworkers36 obtained 4-0-(2-acetamido-3,4,6-tri-O- acetyl - 2 - deoxy -/ - d- glucopyranosyl) -N- (benzyloxycarbonyl)homo-serinamide (164) by coupling 2-acetamido-3,4,6-tri-0-acetyl-2-deoxy-a-D-glucopyranosyl chloride (6) with 2-N-(benzyloxycarbonylamino)-4-hydroxybutanamide128 (163) in the presence of mercury dicyanide. 

Ci4H1gC109 Tetra-O-acetyl-a-D-glucopyranosyl chloride ACGLUP 31 368... 

C-Glucosidation. Reaction of the protected a-D-glucopyranosyl chloride 1 with silyl enol ethers activated with AgOTf results in a-C-glucosyl esters or ketones. 

Glycosidation (13,302). Glycosidation of 2-acetamido-3,4,6-triacetyl-2-deoxy-a-D-glucopyranosyl chloride (1) mediated by Sn(OTf)2 provides exclusively P-glycosides. The most satisfactory base is 1,1,3,3-tetramethylurea, and CH2CI2 is the preferred solvent.2... 

The product is scraped from the walls of the flask and broken up by means of a curved spatula. The solid is collected on a 12.5-cm. Buchner funnel, washed with two 150-ml. portions of dry ether, dried by suction on the filter for 5 minutes, and stored in a desiccator over sodium hydroxide and phosphorus pentoxide. Analytically pure 2-acetamido-3,4,6-tri-0-acetyl-2-deoxy-a-D-glucopyranosyl chloride is obtained weight 55-65 g. (67-79%) m.p. 127-128° (Fisher-Johns apparatus) (Note 7) typical — NHCOCH3 absorptions at 6.09 n and 6.49 n in the infrared. Evaporation of the mother liquors and addition of ether to the concentrated solution gives an additional 4-6 g. (5-7%) of crystalline product, m.p. 125-127°, that is sufficiently pure for most purposes. The pure product may be stored in an open dish in a desiccator at room temperature for at least 3 years without decomposition (Note 8). 

Glycosidation. The silver imidazolate-HgCl2 system favors formation of a-glucosides from reaction of 2,3,4,6-tetra-O-benzyl-a-D-glucopyranosyl chlorides and -a-D-gallactopyranosyl chlorides with sterically hindered alcohols. Addition of tetra-u-bulylammonium chloride (1.4 equiv.) enhances the rate.1... 

Tetra-O-acetyl-a-D-glucopyranosyl Chloride, R. U. Lemieux, Methods Carbohydr. Chem., 2 (1963) 223-224. 

In 1945, Hurd and Bonner129 130 reported the reaction of either tetra-O-acetyl-a-D-glucopyranosyl chloride or penta-0-acetyl-/3-D-glucopy-ranose with benzene in the presence of aluminum chloride, to form 1,2-/rans-/3-D-glucopyranosylbenzene. The implication of the above results (on /3-D-glucoside formation) in connection with the nature of this latter reaction is obvious. 

C20H24CINO9 3,4,6-Tri-0-acetyl-2-deoxy-2-carbo-benzyloxyamino- a-D -glucopyranosyl chloride 13... 

---