Process for producing 13-cis retinoic acid

A process for producing a compound of formula IV:

• 6
• comprising the steps of:
• a). reacting in a solvent in the presence of a weak base, a butenolide of the formula II:
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• with a salt of the formula:
• 8
• where R1, R2 and R3 are independently selected from aryl or dialkylamino, R4 and R5 are independently selected from hydrogen, loweralkyl, alkoxy, cycloalkyl, aryl, or heterocyclic, and X is selected from halogen or hydrogen sulfate, to form a reaction mixture;
• and
• b). recovering the compound from the reaction mixture.