NOVEL PALLADIUM-CATALYZED CARBONYLATION OF ORGANIC HALIDES BY CHLOROFORM AND ALKALI

Aromatic, vinylio, and benzylic halides were catalytically carbonylated by CO generated in situ from chloroform and aqueous alkali, in the presence of tertiary phosphine-palladium complexes (1-5 mol %). The carbonylation occurred at ambient temperature under N2, affording the corresponding carboxylic acids in up to 92% isolated yield. Under the same conditions, benzal bromide underwent catalytic reductive coupling to a 1:4 mixture of cis- and trans-stilbenes. A labeling experiment with (CHCl3)-C-13 showed that the source of the C1 unit in the carbonylation is chloroform. Triphenylphosphine complexes of ruthenium, rhodium, and palladium were found to catalyze the alkaline hydrolysis of chloroform to carbon monoxide. A carbonyl complex, [(Ph3P)2Rh(CO)Cl], was synthesized by treatment of Wilkinson's catalyst with chloroform in the presence of KOH.