Cardenolide synthesis

Two syntheses have been reported for 14j8-hydroxyandrostan-17-ones which are useful intermediates in cardenolide synthesis. Photo-oxygenation of 5a-androsta-14,16-diene gave the epidioxide (296) which was transformed with base into... 

Carbon monoxide, evolution from cellulose on beating, 428, 429 Carbonylation, of alkyl balides, 61 Carbonyl groups, formation from cellulose on heating, 426, 428, 435 Carboxyl groups, formation from cellulose on beating, 426, 427, 435 Cardenolides, synthesis of 1,2-cis-, 267 Cellobiose, /8-, mutarotation of, 23 Cellulase, 376 Cellulose... 

The coupling of enol triflates with y-hydroxycrotonic esters gives butenolides. The method is suitable for cardenolide synthesis. Nonactivated alkenes also undergo coupling. ... 

Because of this situation, the prospect of synthesizing D-rhamnosyl cardenolides containing the unnatural, a-D-linkage was investigated. D-Rhamnose has not been reported to occur naturally, but it has been synthesized by Hudson and co-workers (4) in six steps, starting with methyl a-D-mannopyranoside. An intermediate in the synthesis is methyl... 

Because a substantial excess of the halide is used in the Koenigs-Knorr synthesis of cardenolides, it is usually difficult, if not impossible, to secure the acylated intermediate in crystalline form. Hence, Reichstein nd coworkers18 introduced a procedure whereby the whole of the products arising from the coupling reaction are saponified, employing a solution of potassium hydrogen carbonate in aqueous methanol. This modified transesterification procedure renders all extraneous carbohydrate materials water-soluble the methanol is removed by evaporation, leaving an aqueous solution from which the (deacylated) cardenolide may be obtained by... 

Following this work, Reichstein and coworkers15 effected the first partial synthesis of a naturally occurring cardenolide, convallatoxin. Convalla-toxin [3/3-0-(6-deoxy-a-n-mannopyranosyl) strophanthidin (9)] is considered to be the most potent of all the known, naturally occurring cardenolides, and is obtained from the blossoms of the lily-of-the-valley (Convallaria majalis). The coupling of strophanthidin (2) with 2,3,4-tri-0- acetyl-6-deoxy-a- L-mannosyl bromide was performed using silver car-... 

The preparation of (71) is given in the following experiment, which serves to typify the synthesis of a 2-deoxycardenolide, starting with a 2-deoxy sugar. The experiment also embodies a Meystre-Miescher type of azeotropic distillation technique for removing the water, and saponificar tion catalyzed by potassium hydrogen carbonate for isolation of the unsubstituted cardenolide. 

Lithium, l,3-(cis, trans)-diphenyl-2-azaallyl-generation, 7, 73 Lithium, 5-iodo-2-thienyl-synthesis, 4, 831 Lithium, 2-methoxy-4-furyl-in synthesis of digitalis cardenolides, 1, 423 Lithium, 5-methoxy-2-thienyl-reactions... 

Mu-Methyl eardenolides. A synthesis of 17a-methyl cardenolides (4)1 involves... 

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