Phase Transfer-Catalyzed Enantioselective Mannich Reaction of Malonates with alfa-Amido Sulfones.
Francesco Fini, Luca Bernardi, Raquel P. Herrera, Daniel Pettersen, Alfredo Ricci, Valentina Sgarzani. Phase Transfer-Catalyzed Enantioselective Mannich Reaction of Malonates with alfa-Amido Sulfones.. Adv. Synt. Catal.. 2006, Vol. 348 / 2006, p. 2043-2006.
<p>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 b-amino acids.</p>
<p>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 b-amino acids.</p>