General steroid formula

Altering the stereochemistry at any of the ring-juncture with a heavy-dark line (see general steroid formula s Fig. 23.1) changes immensely the prevailing shape of the steroid , as may be observed in the above cited examples of S -androstane and 5a, 8a-androstane. 

Initial steroid research involved isolation of sterols and bile acids from natural sources. DeFourcroy is generally credited with the discovery of cholesterol [57-88-5] (2) in 1789 (3). In 1848, cholic acid [81-25-4] (3) was isolated from the saponification of ox bile and its elementary composition determined as C24H4QO5 40 years later, Reintzer established the molecular formula of cholesterol as Degradative studies revealed the relationship of cholesterol... 

When it comes to physicochemical (biological) properties the common structural formulae obscure rather than explain the problem. One of the most convincing examples may be the anaesthetic activity of chemicals. Among general anaesthetics one can identify such diverse chemical families like hydrocarbons, alcohols, ethers, barbiturates, nitrous oxide, steroids, etc. Each one must have anaesthetic activity encoded in its structure but how is it discovered using conventional chemical symbolic The planar or three-dimensional chemical notation can be an obstacle to making a breakthrough in chemistry. 

Cholesterol (p. 507), notorious as the substance deposited on the walls of arteries and as the chief constituent of gallstones, is the kind of alcohol called a sterol. Sterols belong, in turn, to the class of compounds called steroids compounds of the general formula... 

Inspection of molecular rotations [M] (589 nm) for a large number of hydroxy-and halogeno-derivatives of steroids has led to empirical rules expressed (for a compound RX) by the general formula... 

A report mentions the synthesis of intermediates of type (68) and (69) for the preparation of c-nor-D-homo-steroids." Compounds of general formula (70)... 

Just as cyclohexane can be drawn in a chair conformation, the three-dimensional representation for 5a-cholestane is shown by the following conformational formula. Although cyclohexane may undergo a flip in conformation, steroids are rigid structures, because they generally have at least one trans fused ring system and these rings must be diequatorial to each other. 

Bufadlenolldes (5j3-bufa-20,22-dienolides). General name for compounds with the steroid basic skeleton shown in the formulae with cis-linkage of rings A and B (5 ff) and C and D (l4pH) as well as 17/3-oriented a- pyrone group. The (20/ )-20,21,22,23-tetrahydro compound is known as 5j3-bufanolide. B. are related to the cardenolides in their chemistry and biological activities. Compounds with this basic structure occur... 

The natural compounds containing this ring, the steroids, are oxygenated, alkyl-substituted derivatives of the hydrocarbon, having the following general formula, where R and R vary from compound to compound ... 

Aromatic compounds, based on the benzene ring structure, with the general formula C H2 6, occur in petroleums in amounts usually less than 10%. Aromatics are al their most concentrated in the denser grade heavy oHs, bitumens and asphalts. Other minor constiments are acycHc isoprenoids (a series based on isoprene, C5Hg, from which synthetic rubbers are derived), steroids (complex ring alcohols based on cyclohexane) and triterpenoid alcohols (with general formifla, [CsHg] ). 

Since the text refers to the formulae of the various steroids from time to time, a numbered general formula is reproduced here to assist the reader. 

It is possible to represent the formulas of the unnatural Z-enantiomers in the mirror projection (297) . however, it is more striking to illustrate them with changed symbols for the a - and -bonds (298). In this book, the structural formulas illustrating compounds with asymmetric carbon atoms not separated into optical antipodes arbitrarily represent one enantiomer (generally the cZ-enantiomer), but they everywhere refer to the racemic dl > compounds. The prefix dl is omitted in the text and all steroids and intermediates must be regarded as racemates unless otherwise specified. As a rule, the steroid numbering of the carbon atoms is used to describe intermediates it must therefore be borne in mind that the attachment of a numerical subscript to a carbon atom (Cg, C21, etc.) always means... 

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