Steroidal Structures

W. L. Duax and D. A. Norton, of Steroid Structure, lEI/Plenum Data, New York, 1975 Terpenoids and Steroids, Vol. 4, The Chemical Society,... 

Table 2-1 gives the percentage or ratio of the epimers formed in a number of reductions covering a wide variety of steroids. Structures (10), (11) and (12) show typical percentages of the predominant epimer formed at various positions in 5a-,5j - and A -steroids. 

Chemical Name 170-hydroxyestr-4-en-3-one 3-phenylpropionate Common Name 19-nortestosterone (3-phenylpropionate Structural Formula See Nandrolone Decanoate for the steroid structure Chemical Abstracts Registry No. 62-90-8 434-22-0 (Base)... 

At elevated temperatures in the presence of oxygen the aluminium oxide layer catalyzes the formation of blue fluorescent aluminium oxide surface compounds with 4-hydroxy-3-oxo-A -steroid structures [4]. Aluminium oxide acts as an oxidation catalyst for an activated methylene group. 

The steric bulk of steroid structures prevents their use as the only organic side group present. However, mixed-substituent polymers that contain both steroidal side groups and amino acid ester or other cosubstituent units can be readily synthesized. If a saturated A ring is present in the steroid, linkage to the polymer chain is complicated by side reactions that result from dehydration of the steroid (chlorophosphazenes are powerful dehydrating agents). 

A tandem Sakurai-carbonyl-ene sequence was used to create a tricyclic skeleton in the synthesis of a steroidal structure.50... 

Reduction of dienes incorporated into steroid structures may lead to different configurations in the products. For example, treatment of 8(9),14(15)-bisdehydroestrone 42 (R = H) for four hours at room temperature with twenty equivalents of trifluoroacetic acid and two equivalents of triethylsilane leads to an ionic hydrogenation product mixture containing the natural 8/1,9a,14a-estrone 43 as a minor component (11%) and the 8a,9/i, l 4/i-isomcr 44 as the major component (83%) (Eq. 92).241 The related methyl ether (42, R = Me) behaves in a similar fashion.241 The yield of natural isomer 46 formed from the methyl ether of A8(9),i4(i5)-bigdehydroestradiol analog 45 increases from 22 to 34%, and that of... 

Figure 6. Construction of steroid structural analogues based on the square pyramidal Re03+ core.

Figure 9.14 A steroid glycoside. Digitoxenin is a cardiac-stimulating drug. It is a steroid glucoside in which a compound with a steroid structure is linked to a-D-glu-copyranose by condensation of the anomeric hydroxyl group on the carbohydrate and the alcohol group at position 5 on the steroid nucleus.

Sterols are compounds that have a steroid structure (Figure 12.5) and contain a hydroxyl group, which is capable of forming an ester. They are widespread in nature and commonly exist as mixtures of the free sterol and esters with fatty acids. Cholesterol (Figure 12.5) is by far the commonest sterol in animals, a high concentration being found in brain, nervous tissue and membranes. Plants... 

The steroids are a remarkable family of molecules. They are essential for health, responsible for the characteristics of our genders, useful medicinal agents, and drugs of abuse. Modest structural variations on the central theme of steroid structure profoundly alter the physiological response to the action of these molecules. Small differences in structure can create big differences in function. 

Cyclic tellurides, including some with a steroidal structure, - have been prepared by the Rongalite method. 

The three most important groups of steroids are the sterols, bile acids, and steroid hormones. Particularly in plants, compounds with steroid structures are also found that are notable for their pharmacological effects—steroid alkaloids, digitalis glycosides, and saponins. 

The most important steroid hormones in vertebrates are listed on p. 57. Calcitriol (vitamin D hormone) is also included in this group, although it has a modified steroid structure. The most important steroid hormone in invertebrates is ecdysone. 

Fusidic acid is a product of, among others, the fungus Fusidium coccineum. It has a steroidal structure and has mainly bacteriostatic activity. Its mechanism of action is based on inhibition of bacterial protein synthesis. Its indications are limited to the treatment of severe staphylococcal infections, usually in combination with another antistaphylococcal agent to prevent the emergence of resistance. 

Table 4.3 summarises the absorption data for some steroid structures and illustrates the effect of molecular weight on the A (1%, 1 cm) value. The strength of the enone chromophore is similar for all the steroids since the A (1%, 1 cm) value is based on the absorption of a 1 % w/v solution it will thus decrease as the molecular weight of the steroid increases. This is of course true for all molecules. 

The third class of lipids is steroids. Included in this category of lipids are cholesterol, bile salts, and sex hormones. Steroid structures contain fused rings consisting of three six-carbon rings and a five-carbon ring ... 

In addition to estrogen agonists based on steroid structures, a variety of nonsteroidal estrogens have also been synthesized and used clinically dienestrol (5.30), diethyl-stilbestrol (5.31), benzestrol (5.32), hexestrol (5.33), methestrol (5.34), methallenestril (5.35), and chlorotrianisene (5.36). 

Alkylation of the partial steroid structure 8 proceeds very similarly5. Alkylation with the fluorinated side chain (( )-9 is claimed to proceed with less than 5% of the (20S)-isomer. 

Enzyme kinetic studies of inhibitor are very important for considering as a therapeutic agent. It is interesting to note that isoprenoid-substituted flavonoids having non-steroidal structures are potent un-competitive inhibitors of 5a-reductase. So, it would be expected that the isoprenoid-substituted flavonoid derivative would be an interesting lead compounds for testosterone 5a-reductase inhibitor. 

Buu-Hoi, N. P., Lambelin, G., Lepoivre, C., Gillet, C., Gautier, M., Thiriaux, J. [A new anti-inflammatory agent of non-steroid structure p-butoxyphenylacethydroxamic acid], Hebd. Seances Acad. Sci. 1965, 261, 2259-2262. 

The Held of steroid analysis includes identification of steroids in biological samples, analysis of pharmaceutical formulations, and elucidation of steroid structures. Many different analytical methods, such as ultraviolet (nv) spectroscopy, infrared (ir) spectroscopy, nuclear magnetic resonance tnmr) spectroscopy, x-ray crystallography, and mass spectroscopy, are used for steroid analysis. 

Ituax, W.L. and D.A. Norton Atlas of Steroid Structure, lFI/Plenum Data. New York, NY. 1975. 

The following problems illustrate the steps taken in several important syntheses of naturally occurring substances. Show the reagents, conditions, and important intermediates you expect to be successful in achieving each of the indicated transformations, noting that more than one step may be required. Except where conditions and reagents already are supplied, all the reactions necessary have been discussed in previous chapters. We suggest that the reasons for the stereospecificity of the reactions (if any) be considered carefully. See Table 30-2 for steroid structures. 

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