STEROIDS

**Definition:** This place covers:

Compounds containing a cyclopenta[a]hydrophenanthrene skeleton (see below) or a ring structure derived therefrom:

Preparation of steroids including purification, separation, stabilisation or use of additives unless provided for elsewhere, as specified below.

Treatment and modification of steroids provided that

**Limiting references (this place does not cover):** - Seco-steroids -> C07C - Compounds with a cyclopenta[a]hydrophenanthrene skeleton wherein a carbon atom shared by two steroid rings is replaced by a heteratom -> C07D - Fermentation or enzyme-using processes to synthesise steroids -> C12P33/00 - Electrolytic production of organic compounds -> C25B3/00

**Glossary:** - A-, B-, C- or D-homosteroid: Compound in which a cyclopenta[a]hydrophenanthrene skeleton is modified by expansion of rings A, B, C or D correspondingly by one atom (the prefix "homo" may also mean that one methyl or methylene group is added in certain position, e.g. 18-homosteroids). - A-, B-, C- or D-bishomosteroid: Compound in which a cyclopenta[a]hydrophenanthrene skeleton is modified by expansion of rings A, B, C or D correspondingly by two atoms. - A-, B-, C- or D-norsteroid: Compound in which a cyclopenta[a]hydrophenanthrene skeleton is modified by contraction of rings A, B, C or D correspondingly by one atom (the prefix "nor" may also mean that one methyl group in certain position is substituted by hydrogen atom, e.g. 19-norsteroids, or one methylene group among non-ring members in certain position is absent). - A-, B-, C- or D-bisnorsteroid: compound in which a cyclopenta[a]hydrophenanthrene skeleton is modified by contraction of rings A, B, C or D correspondingly by two atoms. - "alpha": relates to stereoisomers and designates atoms or groups of atoms that are arranged below the plane of a ring system (the bond between such atoms or groups of atoms and a ring system is represented by a dotted line) provided that a cyclopenta[a]hydrophenanthrene skeleton is drawn on the plane so that rings A, B, C and D are arranged from left to right. - "beta": relates to stereoisomers and designates atoms or groups of atoms that are arranged above the plane of a ring system (the bond between such atoms or groups of atoms and a ring system is represented by a thick or uninterrupted line) provided that a cyclopenta[a]hydrophenanthrene skeleton is drawn on the plane so that rings A, B, C and D are arranged from left to right. - Bile acids: Steroids having a hydroxy-group and a five-carbon-atom side-chain terminating in a carboxyl group, e.g. cholic acid. - Normal steroid: Compound containing non-modified cyclopenta[a]hydrophenanthrene skeleton. - Seco-steroid: Compound which can be obtained from steroids by a break of one of the bonds in cyclopenta[a]hydrophenanthrene skeleton. - Sterols: Steroid alcohols; contain cyclopenta[a]hydrophenanthrene skeleton plus an 8 to 10-carbon atom side-chain and a hydroxy-group, e.g. cholesterol, ergosterol". - Substitution of steroids in certain position: means substitution of hydrogen atom bound to the carbon atom of the cyclopenta[a]hydrophenanthrene skeleton in that position.