Digitoxigenin, structure

Digitoxigenin, structure of, 1097 Digitoxin, structure of, 989 Dihalide, alkynes from, 261 Dihedral angle, 94 Diiodomelhane. Simmons-Smith reaction with, 228-229 Diisobutylaluminum hydride, reaction with esters, 812 structure of, 699 Diisopropylamine, pK.d of, 923 1,3-Diketone, pfCa of, 852 Dimethyl disulfide, bond angles in, 20 structure of, 20 Dimethyl ether, electrostatic... 

A clue to a possibly correct assessment of the conformations of a-L- and of jS-D-cardenolides is provided by the infrared absorption spectra2 of the a-L-rhamnoside [evomonoside (10)3 and the synthetic a-D-rhamnoside (27) of digitoxigenin (1). The two spectra are so similar that only on very close scrutiny can minor differences be observed indeed, they are almost superposable. This fact suggested that the vibrational characteristics of the two molecules are nearly identical. Their structures might, then, be represented as shown, in which both have equivalent conformations. It is... 

Figure 1. PROPHET (a) top and (b) side views of the molecular structure of digitoxigenin lb from crystallographic coordinates...

In the case of the anticalin DigA16, crystal structures were solved not only for the bound digoxigenin but also for the complex with the related steroid digitoxigenin and for the uncomplexed apo-protein [56]. The crystals, which were grown at pH 7.6-8.0 and whose structures were refined to resolutions between 1.8 and... 

Cardenolides. The synthesis of digitoxigenin was announced, while cardenolides of novel structure were described by the Ayerst chemists. " Reichstein and his group are continuing their work on the structure determination of various natiiral cardenolides. ... 

A synthesis of the 17/3-[3-pyrrolin-2-on-4-yl]androstane (361) from acetyl-digitoxigenin (339) has been reported. The conversion of the iV-acetyl compound (362) into dihydrosolacongestidine (363) was improved by use of BU2AIH and thereby improved the synthesis of solacongestidine (364). Addition of diarylnitrilimines to a series of 17-substituted androst-16-enes gave the [16a,17o -f ]-2 -pyrazolines (365) or, when R = OAc, the [16,17-rf]-pyrazoles (366). The pyrazolines (367) were synthesized from 3/3-acetoxy-21-benzylidenepregn-5-en-20-one by reaction with phenyl- or p-methoxyphenyl-hydrazine. " Reaction of cholest-4-en-6-one with hydrazines and o-phenylenediamine led to the heterocyclic structures (368) and (369)... 

Figure 4.7. Shape of the molecular electrostatic potential in the outer space of digitoxigenin when occupying the probable receptor-bound conformation. Using the co-ordinates derived from X-ray crystal structure analysis, the equipotential energy contours (expressed in kJtmol) are calculated with the use of an optimized monopol expansion. The energy contours refer to the plane laid across carbon atoms 6, 8, and 9 involved in forming rings B and C. Reproduced from [128],...

Fig. 1. Structural formula for digitoxigenin cyclopentaperhydrophenanthrene nucleus, unsaturated lactone ring attached at C-17...

Cardenolide structure is closely related to bufadienolides, but these 23C steroids possess a butenolide ring located at C17. As potent cardiotonics, they are widely distributed in plants mostly as glycosides. Digitoxigenin is a typical example of cardenolides. Besides, they are either toxins or insect deterrents. 

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