Continued from 3S-4. Functional groups (3S-4.0 to 3S-4.3)
3S-4. Functional groups (continued)
4.4 Oxo compoundsReferences for this section
4.8 Acetals and ketals
4.9 Trivial names of important steroids
4.10 Use of international non-proprietary names
(a) Aldehydes are named by using either the suffix -al (denotes change of -CH3 to -CHO, i.e. without change in the number of carbon atoms), or -aldehyde (denotes change of -COOH to -CHO, i.e. without change in the number of carbon atoms; the name is derived from that of the acid). The prefix oxo- denotes the change of >CH2 to >CO, thus also of -CH3 to -CHO, with no change in the number of carbon atoms. Examples:
If the aldehyde group is formed by substitution of a hydrogen atom in CH, >CH2 or -CH3 by -CHO i.e. C-CHO the prefix formyl or suffix carbaldehyde is used. Examples:
(b) For ketones, the suffix is -one, and the prefix oxo-. Examples:
(1) The prefix oxo- should also be used in connection with generic terms, e.g. 17-oxo steroids. The term "17-keto steroids", often used in the medical literature, is incorrect because C-17 is specified twice, as the term keto denotes C=O.
(2) Many steroids carry hydroxyl groups as well as oxo groups. In this case, the suffix -one must be used, and hydroxyl groups indicated by prefixes, unless the compounds have trivial names (see Table 2). If the principal functional group (and hence the suffix) is preferred to either hydroxyl or oxo groups both hydroxyl and oxo groups are indicated as prefixes.
Alcohols are named with the suffix -ol or the prefix hydroxy-, with the appropriate locants. Examples:
(1) Composite suffixes -olone and -onol, to denote simultaneous presence of hydroxyl and ketonic groups, are not permitted by IUPAC Recommendations  and should not be used.
(2) A few trivial names exist for hydroxy ketones (see Table 2).
Amines are named by means of the suffix -amine or the prefix amino-. Examples:
Ethers are named as alkoxy derivatives. Examples:
Ethers and partial ethers of steroid polyols are named either by using the alkoxy- prefix, or by the prefix O-alkyl- if the hydroxy group etherified is already specified in a trivial name. Examples:
3S-4.8. Acetals and ketals
Acetals and ketals of oxo steroids are named as dialkoxy steroids. Examples:
Similarly, acetals formed by an oxo compound reacting with two hydroxyl groups of a steroid may be named alkylenedioxy compounds. Example:
3S-4.9. Trivial names of important steroids
Examples of trivial names retained for important steroid derivatives, these being mostly natural compounds of significant biological activity, are given in Table 2.
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Table 2. Trivial names of some important steroid derivatives
|Trivial name||Systematic steroid name|
|Aldosterone||18,11-hemiacetal of 11,21-dihydroxy-3,20-dioxopregn-4-en-18-al or 11,18-epoxy-18,21-dihydroxypregn-4-ene-3,20-dione|
|Calciol = cholecalciferol(92)||(5Z,7E)-(3S)-9,10-secocholesta-5,7,10(19)-trien-3-ol|
|Cholic acid||3,7,12-trihydroxy-5-cholan-24-oic acid|
|Deoxycorticosterone||21-hydroxypregn-4-ene-3,20-dione (i.e. the 11-deoxy derivative of corticosterone)|
|Ercalciol = ergocalciferol||(5Z,7E,22E)-(3S)-9,10-secoergosta-5,7,10(19),22-tetren-3-ol|
|Lithocholic acid||3-hydroxy-5-cholan-24-oic acid|
Note If these trivial names are used as a basis for naming derivatives or stereoisomers, the derived trivial name must make the nature of the modification completely clear and is preferably accompanied at first mention by the full systematic name. For example, in steroid papers epi is often used with trivial names to denote inversion at one centre; the name 11-epicortisol defines the compound fully since cortisol is already defined as the 11-alcohol; but the name epicortisol does not define the compound and is inadequate.
3S-4.10. Use of international non-proprietary names
International non-proprietary names (INNs) have been given to many steroids of pharmaceutical importance . For convenience, a selection of some of these names is given in the appendix. If these names are used in biochemical papers, it is recommended that once in the paper, e.g. in a footnote or under Materials and Methods, the full systematic name is also given. International non-proprietary names should not be used as a basis for the names of modified compounds.
2. International Union of Biochemistry (1978) Biochemical nomenclature and related documents, The Biochemical Society, London.
3. International Union of Pure and Applied Chemistry, Nomenclature of organic chemistry, Sections A, B, C, D, E, F and H, 1979 Edition, Pergamon Press, Oxford, 1979. Section E appeared also in pp. 1-18 of , and section F in pp. 19-26 of  and in Eur. J. Biochem. 86, 1-8 (1978).
6. International non-proprietary names (INN) for pharmaceutical substances, cumulative list 6, World Health Organization, 1982.
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