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On Cardioactive Steroids. XVI. Stereoselective β‐Glycosylation of Digitoxose: The Synthesis of Digitoxin
Author(s) -
Wiesner Karel,
Tsai Thomas Y. R.,
Jin Haolun
Publication year - 1985
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19850680203
Subject(s) - chemistry , aglycone , stereoselectivity , digitoxigenin , digitoxin , glycosylation , furan , stereochemistry , catalysis , glycoside , organic chemistry , biochemistry , digoxin , heart failure , medicine
Two methods for stereoselective β‐glycosylation of digitoxose were developed. The first achieved stereocontrol by a 1,3‐participation of a N ‐methylurethane group under acid catalysis. The second utilized mercuric‐ion catalyzed cleavage of thioglycosides and a 1,3‐participation of a p ‐methoxybenzoyl group in a neutral medium. The first highly stereoselective and quite efficient synthesis of digitoxin ( C7 ) was achieved by a combination of these methods. The furyl‐substituted precursor IV of digitoxigenin ( Scheme 1 ) was used as aglycone, and the furan group was converted to the unsaturated lactone of digitoxin by our known oxidation procedure ( m ‐chloroperbenzoic acid/NaBH 4 ) after the assembly of the carbohydrate portion of the molecule and its deblocking was completed.