Selective isomerization–carbonylation of a terpene trisubstituted double bond

Abstract

Selective catalytic carbonylation of the trisubstituted double bond of citronellic acid is enabled via an isomerization–functionalization approach. Alkoxycarbonylation with [{1,2-(^tBu₂PCH₂)₂C₆H₄}Pd(OTf)₂] as a catalyst precursor occurs with >97% selectivity for the terminal diester dimethyl-3,7-dimethylnonane-dioate. This prevails much over the typical cationic methoxyaddition. The reactive primary carboxy group formed allows for e.g. the preparation of the high molecular weight novel polyester poly[3,7-dimethylnonanediyl-3,7-dimethylnonanedioate].