Synthesis of New Chiral N-alkyl Betti-base Ligands via One-Pot Three Component Strategy

Abstract

Background: Betti base derivatives were employed as chiral ligands or as chiral auxiliaries in asymmetric transformations. In particular, N-alkyl Betti base derivatives are gaining importance as excellent ligands in asymmetric reactions. However, no appropriate method exists for regioselective N-alkylation of Betti base. Therefore, there is an urgent need to develop a new protocol for the regioselective N-alkylation of chiral Betti-base. Methods: An efficient method has been developed for one-pot synthesis of chiral N-alkyl Bettibase ligands from (S)-(+)-Betti base, arylglyoxals and cyclic 1,3-C,N-binucleophiles under catalyst- free conditions. Results: The chiral N-alkyl Betti-base ligands were obtained in good yields with excellent enantioselectivities. This method is rapid, clean and does not require a catalyst or chromatographic purification. Conclusion: We have developed an efficient one-pot three component strategy for the synthesis of new chiral N-alkyl Betti-base ligands from (S)-(+)-Betti base, arylglyoxals and cyclic 1,3-C,Nbinucleophiles in the absence of a catalyst.