Alfonso de Dios

Highly diastereoselective bis-hydroxylation of the amino-deoxy-conduritol C ring system. A formal synthesis of the aminocyclitol moiety of the antibiotic Hygromycin A

Abstract A formal synthesis of the aminocyclitol fragment of the antibiotic Hygromycin A is reported using, as a key step, a highly diastereoselective bis-hydroxylation of an amino-deoxy-conduritol C derivative, easily accesible from an 7-oxanorbornenic derivative which in turn can be synthesised from furan.

Highly diastereoselective bis-hydroxylation of a protected conduritol B: a short route to myo-inositol derivatives.

Abstract Glycosyl-7-oxanorbornanes; Stereoselective Reduction; Conduritol B; Bis-Hydroxylation: myo -Inositol Derivatives Model studies on a synthesis of glycosylinositols via glycosyloxanorbornanes have resulted in a shoft and highly stereoselective synthesis of conveniently protected myo-inositols from 7-oxanorbornen-2-one featuring a highly diastereoselective catalytic osmylation of a protected Conduritol B.

Synthesis of optically pure, differentially protected 1,4- and 1,6-mannosyl-D-myo-inositol derivatives from 7-oxabicyclo[2.2.1]heptan-2-one

Abstract Efficient procedures to prepare 4- O -mannosyl conduritol B derivatives from mannosyl oxanorbornanes are described. The osmium-catalyzed cis -dihydroxylation of the corresponding 1- O -acetates displays high π-facial selectivity syn to the acetate functionality to produce 1,4- and 1,6-mannosyl-D- myo -inositol derivatives.

Polar vs steric effects in the 1,3-dipolar cycloaddition reactions of acetonitrile oxide and 2-endO-acetoxy-5-halo-7-oxabicyclo[2.2.1]hept-5-en-2-exo-carbonitrile

Abstract The regioselectivity of the cycloaddition reactions between acetonitrile oxide and a number of 7-oxabicyclo[ 2.2.1]hept-5-enes is discussed. Acetonitrile oxide adds with complete regioselectivity to 2- endo -acetoxy-5-halo-7-oxabicyclo[2.2.1]hept-5-en-2-exo-carbonitriles. Kinetic measurements indicate a more polar transition state for 2a than for the unsubstituted substrate la

Sulfoxide-mediated diastereoselective Michael additions. New enantioselective synthesis of C-4 substituted 2-pyroaminoadipic acids

Abstract Diastereoselective reactions of suitably functionalized homochiral β-iminosulfoxides with Michael acceptors provide a new and efficient route for the asymmetric synthesis of C-4 substituted 2-pyroaminoadipates. Extension of the scope of the sulfoxide-mediated aza-enolate conjugate addition (Huas reaction) has also been explored.

Regio- and stereocontrolled alkylative ring opening of unsymmetrical 8-oxabicyclo[3.2.1]octene systems. Synthesis of highly substituted hydroxycycloheptenyl sulfones.

Abstract The organolithium mediated bridge opening of unsymmetrically substituted 8-oxabicyclo[3.2.1]octene derivatives 6, 7, proceeds with complete regio- and stereoselectivity to afford highly functionalized hydroxycycloheptenyl sulfones 10, 12 in high yields. It was also found possible to control the conjugate addition/β-elimination sequence towards the synthesis of adducts 8, 9, 11 .