Retinoid naming systems

To name retinoids systematically (lUPAC nomenclature), however, a different numbering scheme must be used the carbon atom bonded to the functional group is given number 1. The numbering of carbon atoms by this scheme is shown m structure III for a -trans retinoic acid. Accordingly, the systemic name for a -trans retinoic acid is (al trans) 3,7-dimethyl-9-(2,6,6-trimethylcyclohex-l-en-l-yl)-nona-2,4,6,8-tetraen-l-oic acid, or more simply (all-trans) 3,7-dimethyl-9-(2,6,6-trimethylcyclohexene-l-yl)-2,4,6,8-nonatetraenoic acid. 

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