ISSN:
0947-3440
Schlagwort(e):
Glycals, ketose-derived
;
exo-D-Fructal
;
exo-L-Sorbal
;
endo-D-Fructal
;
Elimination, reductive
;
Chemistry
;
Organic Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
The reductive elimination of the benzoylated β-D-fructopyranosyl and α-L-sorbopyranosyl bromides 10 and 23 has been examined in order to determine suitable conditions for effecting the elimination from the exo- as well as the endo-positions. Exposure of 10 and 23 to Zn/HOAc or Zn/N-methylimidazole gave the tribenzoates of exo-D-fructal (1) and exo-L-sorbal (25), in yields of 79 and 80%, respectively; minor products (ca, 10% each) were the corresponding endo-D-fructal (6) and endo-L-sorbal esters (26). For the reductive elimination to occur primarily from the endo-position, enhancement of the leaving group capacity of the respective ring acyloxy group was required, and materialized via the 3-O-mesyl analogues of fructosyl bromide 10, which smoothly reacted with Zn/HOAc to give the endo-D-fructal esters 20 and 21; their yields, over the five steps from diacetone-fructose, were in the 50% range. Accordingly, the methodology for generating ketose-derived glycal esters in exo- or endo-version, is now available. Some ensuing reactions of the exo-glycals have been exploited, that is, their ozonolysis to the respective pyranoid pentonolactones, and their hydrogenation to 1,5-anhydro-6-deoxy-hexitols.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/jlac.1995199512293
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