Synthesis Of 2-Deoxy-L-ribose And 3, 4, 5-Trihydroxypiperidines

This thesis contains two major parts, the syntheses of 2-deoxy-L-ribose and two 3, 4, 5-trihydroxy piperidines.The first part of this thesis describes the synthesis of 2-deoxy-L-ribose (Fig.1).Deoxyribose ,the component of DNA for express human genetic information, is very important,nucleoside have been attracted widely attention in biology, medicine, and other fields,and which can be synthesized by deoxyribose. 2-deoxy-L-ribose would be the central building block for the syntheses of modified nucleosides enantiomer, which may have great potential as useful antiviral agents. Therefore the synthesis of 2-deoxy-L-ribose has been a very interesting subject for the synthetic chemists.Starting from D-(-)-ribose, acetonide formation on the diol,followed by Wittig reaction of the lactol, primary alcohol was converted into the corresponding benzyl ether, oxidation of this alkene to the aldehyde and removed the protecting group of acetonide, final deprotection of the benzyl ether using transfer hydrogenation resulted in the production of 2-deoxy-L-ribose in 13% overall yield as anomeric mixture of the furanoside and pyranoside forms (Fig.2).The second part of the thesis describes the synthesis of two 3, 4, 5-trihydroxy piperidines.3, 4, 5-Trihydroxy piperidinesâ…£-â…¦(Fig.3) are a small group of four polyhydroxy piperidine alkaloids,of whichâ…£-â…¥were isolated by Kusano et al in 1995 from Eupatorium Fortunei TURZ,a folk medicinal plant used for the treatment of several ailments. Compoundsâ…£-â…¥have been proven to be the major effective components in Eupatorium Fortunei TURZ. These alkaloids showβ-glucosidase inhibition activity withâ…¤to be the most potent (IC₅₀=3.18μM).Using (2S, 3S)-dihydroxy-lactol prepared from D-(-)-ribose as the starting material, a concise and stereoselective route has been developed for the synthesis of trihydroxy piperidineâ…¤andâ…¥as their hydrochloride. followed by methylenation of the lactol, activation of the primary alcohol by mesylation, epoxidation of the terminal alkene followed by separation of the two isomeric epoxides, nucleophilic displacement of the mesylate and opening of the epoxide forming the piperidine ring, final hydrogenolysis in HCl provides trihydroxy piperidineâ…¤andâ…¥as their hydrochloride in 7 steps in 16% and 8% overall yields respectively (Fig. 4).