Principles of Organic Nomenclature

R-1.2.7 Rearrangement

R- The prefix abeo-. Bond migration, i.e., the formal transfer of one end of a skeletal bond to another position, with a compensating transfer of a hydrogen atom, can be indicated by a prefix of the form "x(y->z)abeo-". This prefix is compiled as follows: a numeral denoting the stationary (unchanged) end of the migrating bond (x) is followed by parentheses enclosing the locant denoting the original position (y) from which the other end of this bond has migrated, an arrow, and the locant (z) denoting the new position to which the bond has moved. The closing parenthesis is followed by the italicized prefix abeo- (Latin: I go away) to indicate bond migration. The original numbering is retained for the new compound and is used for the numbers x, y, and z. It is always necessary to specify the resulting stereochemistry (see also Section F of the 1979 edition of the IUPAC Nomenclature of Organic Chemistry).

Example to R-

R- The prefix retro- indicates a shift, by one position, of all single and double bonds in a conjugated polyene system. In this sense, it has been applied hitherto only to carotenoids (see Section F of the 1979 edition of the IUPAC Nomenclature of Organic Chemistry).

Example to R-

Note: In naming peptides, this prefix is used with a different meaning, i.e., to indicate the change of Ala-Lys-Glu-Tyr-Leu to Leu-Tyr-Glu-Lys-Ala.

R-1.2.8 Multiplicative operation

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