ISSN:
1434-193X
Schlagwort(e):
Carbocycles
;
Carbohydrates
;
Chemistry
;
General Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
-Fucopyranoside analogs with methylene groups instead of endo- or exo-anomeric oxygens, carba- and C-fucopyranosides, respectively, were synthesized. For the synthesis of 5a-carba-L-fucose (1) two approaches were studied, which shared a common cyclitol building block (8), obtained from a SmI2-promoted carbocyclization of a D-mannitol derivative. The first route made use of a Stork radical cyclization onto a conduritol derivative 13 as the key step, which failed to give the silyl ether ring. The second route furnished the target 1, and involved regioselective elimination of a cyclic sulfate 9, and stereoselective hydrogenation of a double bond, controlled by substitution on the substrate. For the synthesis of 1-C-fucopyranosides (37, 38, and 42) a new method based on the use of fucosyl phenyl sulfoxides (35 and 41) was employed. An anomeric carbanion is generated through phenylsulfinyl-lithium exchange, which reacted with electrophiles with retention of configuration at the anomeric center. The required fucosyl sulfoxides were prepared from L-fucose by highly stereoselective thioglycosylation reactions.
Zusätzliches Material:
2 Tab.
Materialart:
Digitale Medien
