Papulacandins and chaetiacandin: a stereoselective route to their basic skeleton by a palladium-mediated arylation of 4,6-O-benzylidene-3-O-tert- butyldimethylsilyl-l-tributyl-stannyl-D-glucal.
Palladium(0)-catalysed coupling of 1,5-anhydro-4,6-O-benzylidene-3-O-tert- butyldimethylsilyl-2-deoxy-1-tributylstannyl-D-arabino-hex-1-eni tol (7) with 3,5-dibenzyloxy-2-bromobenzyl alcohol gave 1,1(2)-anhydro-4,6-O-benzylidene-3-O-tert-butyldimethylsilyl-2-deoxy-1-( 4,6- dibenzyloxy-2-hydroxymethyl-phenyl)-alpha-D-arabino-hexopyranos e (13). The same reaction buffered by sodium carbonate provided 1,5-anhydro-4,6- O-benzylidene-3-O-tert-butyldimethylsilyl-2-deoxy-1-(4,6-dibenzyloxy+ ++-2- hydroxymethyl-phenyl)-D-arabino-hex-1-enitol (11). Stereoselective oxidative spiroacetalisation of 11 provided 1,1(2)- anhydro-4,6-O-benzylidene-3-O-tert-butyldimethylsilyl-1-(4,6-dibenzyl oxy-2- hydroxymethyl-phenyl)-alpha-D-glucopyranose (15), the basic tricyclic structure of papulacandins. In a model study, 15 was converted in three steps into 1,1(2)-anhydro-1-(4,6-dihydroxy-2-hydroxymethylphenyl)-3-O- octadecanoyl-alpha-D-glucopyranose (24), a structural analogue of papulacandin D. Moreover, stereoselective hydroboration-oxidation of 11 furnished 2-(4,6-O-benzylidene-3-O-tert-butyldimethylsilyl-beta-D- glucopyranosyl)-3,5-dibenzyloxy-1-hydroxymethylbenzene (26), the structural skeleton of the chaetiacandin 3.
Dubois
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Laboratorie de Biochimie Structurale, U.R.A. 499, Université d'Orléans, France.
Beau
J M
JM
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents / Q000138:chemical synthesis*; D000935:Antifungal Agents / Q000138:chemical synthesis*; D002236:Carbohydrate Conformation; D003847:Deoxyglucose / Q000031:analogs & derivatives*; D054714:Echinocandins; D007202:Indicators and Reagents; D015394:Molecular Structure; D009904:Optical Rotation; D009942:Organometallic Compounds; D010165:Palladium; D013237:Stereoisomerism
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D054714:Echinocandins; D007202:Indicators and Reagents; D009942:Organometallic Compounds; C074939:4,6-O-benzylidene-3-O-tert-butyldimethylsilyl-1-tributylstannylglucal; D010165:Palladium; C014732:papulacandins; C045691:chaetiacandin; D003847:Deoxyglucose