A process for highly effective regio- and stereoselective palladium-catalyzed allylic substitution of 2,3-unsaturated derivatives of N-acetylneuraminic acid (Neu5Ac2en) has been developed. We show that the efficiency of the allylation reaction depends on suitable protecting groups on the starting material and that, with sodium malonate anion as a nucleophile, the regioselectivity can be fine-tuned by the nature of the ligands associated with the palladium complex. These results are explained by the stoichiometric preparation and study of the highly probable complexes involved in the catalytic reaction. Reactions of this type were also applied to other nucleophiles for the construction of C-C, C-N, and. C-O bonds, leading to the major formation of the C-4 regioisomers. The selective transformation of some of the substitution products provided easy access to a variety of modified sialic acid derivatives that might serve as useful, sialyl building blocks for biological research.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Organic Chemistry