Direct evidence of cis addition in the catalytic hydrocarboxylation of acenaphthylene to acenaphthene-1-carboxylic acid

The hydrocarboxylation of acenaphthylene with the [PdCl2(CH3CN)(2)] + nPAr( 3) catalytic system gave good yields of acenaphthene-l-carboxylic acid, aft er it was found that the chemoselectivity over oligomeric side products is highly dependent on the electronic characteristics of the phosphine and the P/Pd ratio. Deuteriocarboxylation of this substrate has been found useful to determine the diastereoselectivity of this type of reaction, owing to th e structure of the product. A series of results showed that hydrocarboxylat ion of acenaphthylene with oxalic acid and CO at 30 bar is highly diastereo selective in the cis isomer under all tested conditions but one.