A Simple and Highly Diastereoselective One-Pot Synthesis of Mannich-Bases

Michael Arend; Nikolaus Risch

doi:10.1055/s-1997-946

Synlett 1997; 1997(8): 974-976
DOI: 10.1055/s-1997-946

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A Simple and Highly Diastereoselective One-Pot Synthesis of Mannich-Bases

Michael Arend, Nikolaus Risch^*

^*Fachbereich Chemie und Chemietechnik, Universität-Gesamthochschule Paderborn, Warburger Str. 100, D-33098 Paderborn, Germany, Fax +5251/60-3245; E-mail: nr@chemie.uni-paderborn.de

Abstract

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A convenient one-pot procedure for the synthesis of β-amino ketones 5 from economical shelf reagents is described. Iminium salts 3 are generated in virtually quantitative yields from secondary amines 1 and aldehydes 2 mediated by NaI/Me₃SiCl/NEt₃. Subsequently, the salts 3 are used for the in situ aminoalkylation of enamines 4. The method provides the Mannich bases 5 in high yields and excellent diastereoselectivities (>96 % ds). It can also be applied for the aminoalkylation of other nucleophiles such as imines or electron-rich aromatic compounds.

β-amino ketones - diastereoselective aminoalkylation - enamines - imines - iminium salts

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