Lanthanoid-catalysed Tishchenko reaction of mono- or di-aldehydes

Lanthanoid complexes are round to be very active catalysts for the Tishchenko reaction of aldehydes. In the presence or Cp*(2)LnCH(SiMe(3))(2) (Ln = Nd, La), esters are obtained from corresponding monoaldehydes in high yields. This method is applicable to dialdehydes. The reaction of o-phthalaldehyde proceeds intramolecularly to give phthalide quantitatively. Terephthalaldehyde and di(4-formylphenyl) ether are cleanly converted into the poly[p-(carboxymethylene)phenylene] (II) and poly[p-(carboxymethylene)(p-phenylenoxy)phenylene] (III), respectively. On the other hand, isophthalaldehyde polymerizes first and then the polymer is transformed into a macrocyclic lactone 1,5,11-trioxo-2,4; 8,10;14,16-tribenzo-6,12,18-trioxacyclooctadecane (I-a) in high yields. The 18-membered macrocyclic structure of I-a was determined by the X-ray analysis. Stoichiometric reactions of the La complex with benzaldehyde indicated the intermediacy of alkoxo complexes in the catalysis.