The highly enantioselective reaction between in situ generated, Cbz-protected azomethines and malonates in the presence of 150 mol% of potassium carbonate (50% w/w) and 1 mol% of quinine-derived quaternary ammonium bromides as phase-transfer organocatalysts has been developed. This study reports a novel approach for the asymmetric Mannich-type reaction and a wide range of azomethines, including those derived from enolizable aldehydes, is tolerated by the present system. The adducts, obtained in excellent yields with ee up to 98%, are suitable precursors of optically pure β-amino acids.
F. Fini, L. Bernardi, R.P. Herrera, D. Pettersen, A. Ricci, V. Sgarzani (2006). Phase-Transfer-Catalyzed Enantioselective Mannich Reaction of Malonates with alfa-Amido Sulfones. ADVANCED SYNTHESIS & CATALYSIS, 348(15), 2043-2046 [10.1002/adsc.200600250].
Phase-Transfer-Catalyzed Enantioselective Mannich Reaction of Malonates with alfa-Amido Sulfones
FINI, FRANCESCO;BERNARDI, LUCA;RICCI, ALFREDO MARCO;
2006
Abstract
The highly enantioselective reaction between in situ generated, Cbz-protected azomethines and malonates in the presence of 150 mol% of potassium carbonate (50% w/w) and 1 mol% of quinine-derived quaternary ammonium bromides as phase-transfer organocatalysts has been developed. This study reports a novel approach for the asymmetric Mannich-type reaction and a wide range of azomethines, including those derived from enolizable aldehydes, is tolerated by the present system. The adducts, obtained in excellent yields with ee up to 98%, are suitable precursors of optically pure β-amino acids.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
