AUS DEM Diacetat DER 3,4- ö -Isopropyliden-半乳-Verbindung 2 wird第三人以photolytische Desoxygenierung 3 gewonnen,dessen milde Acidolyseつ4 führt。死Acetylierung gibt死单乙酸酯5 UND 6 sowie DAS Diacetat 7。Durch Methylierung von 6 mit重氮甲烷在硼三氟-Katalyse上与das 4 - O -Methyl-Derivat 9 gewonnen,das mit溴三甲基硅酸盐glum zum 2,6-Didesoxyglycosylbromid 8 reagiert。Aus 7 ist entsprechend das Bromid 10erhältlich,das mit der Monohydroxy-Verbindung
Indium-mediated allylation of aldehydes: A convenient route to 2-deoxy and 2,6-dideoxy carbohydrates
摘要:
The allylation of protected polyhydroxy aldehydes 1 and 14 has been achieved by indium metal with ultrasound promotion generating the diastereomeric pair of homoallylic polyols 3, 4 and 16, 17 respectively with moderate to good stereoselectivity. Pursuing this allylation strategy with the corresponding deprotected polyhydroxy aldehydes led to the same pair of homoallylic polyols but with a quite different ratio of the diastereomers generated. The polyols were further transformed to 2-deoxy (5 and 6) and 2,6-dideoxy (18 and 19) carbohydrates by ozonolysis.