ISSN:
0170-2041
Schlagwort(e):
Radical deoxygenation
;
(+)-Catechin epimerization
;
Chemistry
;
Organic Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
On the Radical Deoxygenation of Secondary AlcoholsThe derivatives 1c-1f were prepared from tetramethyl-(+)-catechin (1b). Their radical reduction with tri-n-butyltin hydride or tris(trimethylsilyl)silane in the presence of azobis-(isobutyronitrile) as initiator led to (2R)-( - )-3′,4′,5,7-tetramethoxyflavan (1g). The best yield of 1g (about 75% from 1b) was achieved via the N-(imidazolyl)thiocarbonyl derivative 1c. Analogously the enantiomeric (2S)-(+)-3′,4′,5,7-tetramethoxyflavan (2g) was obtained from tetramethyl-(+)-epicatechin (2b) via 2c. Experimental evidence is given which shows that in aqueous solution, with a catalytic amount of potassium hydrogen carbonate, (+)-catechin (1a) epimerises at the C-2 position of the flavan skeleton to give (+)-epicatechin (2a).
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/jlac.199219920152
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