Titanocene‐Catalyzed Sequential Carbocarboxylation of Dienes and Alkenes with Organic Halides and Carbon Dioxide in the Presence of nBuMgCl

Abstract A titanocene‐catalyzed regioselective carbocarboxylation of dienes or alkenes has been developed. This reaction proceeds efficiently to form flexible and versatile carboxylic acids in the presence of n BuMgCl by the combined use of dienes or alkenes with organic halides and CO 2 as the carbon synthon and carboxyl group, respectively. 2,3‐Disubstituted 1,3‐butadienes were used to afford acrylic acids in excellent yields with various organic halides. In the most cases, the arylalkenes afforded benzylic acids in high yields under similar conditions. The titanocene catalyst plays important roles in the generation of radicals and allyl‐ or benzyl‐magnesium halides.