120316-55-4

Upstream product

• 5707-04-0 Phenylselenyl chloride 
• 563-63-3 silver(I) acetate 
• 120408-91-5 3-O-(tert-butyldimethylsilyl)-6-deoxy-D-glucal 
• 120316-53-2 Acetic acid (2S,3R,4S,5R,6R)-4-(tert-butyl-dimethyl-silanyloxy)-5-hydroxy-6-methyl-3-phenylselanyl-tetrahydro-pyran-2-yl ester 
• 192653-64-8 Acetic acid (2R,3S,4R,6R)-6-[(3S,8S,9S,10R,13R,14S,17R)-17-((R)-1,5-dimethyl-hexyl)-10,13-dimethyl-2,3,4,7,8,9,10,11,12,13,14,15,16,17-tetradecahydro-1H-cyclopenta[a]phenanthren-3-yloxy]-4-hydroxy-2-methyl-tetrahydro-pyran-3-yl ester 

Relevant academic research and scientific papers

Stereoselective synthesis of 2-deoxy-β-glycosides from glycal precursors. 2. Stereochemistry of glycosidation reactions of 2-thiophenyl- and 2-selenophenyl-α-D-gluco-pyranosyl donors

We have demonstrated that 4-O-acetyl-6-bromo-3-O-(tert- butyldimethylsilyl)-2-deoxy-2-thiophenyl-1-trichloroacetimido-α-D- glucopyranose 11b is the most efficient and selective donor for use in the synthesis of 2-deoxy-β-glycosides of the series of glycosyl donors examined. Unlike the 2-selenophenyl substituted donors 8 which proved to be configurationally unstable under standard TMS-OTf promoted glycosylation conditions, giving rise to α-manno glycosides 14, 17 and 20 from β-gluco donors 8, the 2-thiophenyl substituted donors 9 and 11 appeared to be completely configurationally stable (at C(2)). The main problem with imidates 11 is that the stereoselectivity of their reactions with alcohols is substrate dependent, with best selectivity for the desired β-glycosides 35 and 42 being obtained with the least sterically hindered alcohols. The fact that the α-glycosides 36 and 43 comprise up to 20-50% of the product in glycosidation reactions of hindered secondary alcohols supports the thesis that the reaction stereoselectivity is not governed by the intermediacy of episulfonium ions (47 and 47'), but rather that substitution reactions of oxonium ions 46 and its conformationally inverted isomer 46' play a dominant role.

Stereoselective synthesis of 2-deoxy-β-glycosides from glycal precursors. 1. Stereochemistry of the reactions of D-glucal derivatives with phenylsulfenyl chloride and phenylselenenyl chloride

The stereoselectivity of the reactions of D-glucal derivatives with PhSCl and PhSeCl is dependent on the presence of an electronegative heteroatom substituent at C(6) and the nature of the functionality at C(4). The C(6)-substituent influences the conformational preferences of the D- glucal derivatives, and greatest stereoselectivity is obtained with those glycals that preferentially exist in the inverted 5H4 half-chair conformation 28b. A polar substituent at C(4) increases the selectivity by stabilizing the episulfonium/episelenonium ion intermediates 31b and 33.

SELENIUM-MEDIATED GLYCOSIDATIONS: A SELECTIVE SYNTHESIS OF β-2-DEOXYGLYCOSIDES

1,2-Trans diequatorial acetoxy-selenides are selectively prepared from glycals.Their activation by trimethylsilyl trifluoromethanesulfonate in the presence of sugar alcohols followed by reductive deselenation leads to an efficient access to Β-2-deoxyglyco