Synthesis of alpha-heteroarylpropanoic acid via asymmetric hydroformylation catalyzed by Rh(I)-(R,S)-BINAPHOS and the subsequent oxidation.J Org Chem. 2007 Nov 09; 72(23):8671-6.JO
The asymmetric hydroformylation of vinyl heteroarenes (vinylfurans and vinylthiophenes) was investigated by using Rh(I)-BINAPHOS derivatives as a catalyst. The hydroformylation of vinylthiophenes 1 gave the corresponding branched aldehydes 2 with high enantiopurities as major products. Oxidation of the aldehydes 2 successfully afforded alpha-heteroarylpropanoic acids 4 in good yields. In addition, the aldehydes 2 were reduced to alcohols 5 without loss of enantiomeric excess.