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Synlett 2007(15): 2395-2399  
DOI: 10.1055/s-2007-985594
LETTER
© Georg Thieme Verlag Stuttgart · New York

Trimethylsilyl Trifluoromethanesulfonate as a Metal-Free, Homogeneous and Strong Lewis Acid Catalyst for Efficient One-Pot Synthesis of α-Aminonitriles and Their Fluorinated Analogues

G. K. Surya Prakash*, Chiradeep Panja, Clement Do, Thomas Mathew, George A. Olah*
Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California, University Park, Los Angeles, CA 90089-1661, USA
Fax: +1(213)7406270; e-Mail: gprakash@usc.edu;
Further Information

Publication History

Received 20 April 2007
Publication Date:
22 August 2007 (online)

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Abstract

One-pot three-component Strecker reaction of ketones/fluorinated ketones for the preparation of α-aminonitriles/fluorinated α-aminonitriles has been achieved using trimethylsilyl tri­fluoromethanesulfonate [(CH3)3SiOSO2CF3, TMSOTf)] as a metal-free strong Lewis acid catalyst. These reactions are simple and clean, giving the products in high yield and high purity. α-Aminonitriles and their fluorinated analogues are important classes of compounds, which show interesting pharmaceutical and biological properties. Presence of fluorine atom increases their biological ­activities significantly.

Key words

multicomponent reaction - metal-free organocatalyst - TMSOTf - fluorinated ketones - α-aminonitriles

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General Procedure for the Strecker Reaction of Aldehydes and Ketones
Aldehyde or ketone (2 mmol)/fluorinated ketone (3 mmol), amine (2 mmol), TMSCN (3 mmol), and TMSOTf (5 mol%) were taken in CH2Cl2 (5 mL) in a sealed pressure tube and the reaction mixture was stirred at r.t. for several hours. Completion of the reaction was monitored by NMR. After completion, the reaction mixture was quenched with H2O and then extracted with CH2Cl2 (3 × 15 mL). All the organic layers were collected, washed with brine solution, and dried over anhyd Na2SO4. Removal of the solvent under reduced pressure provided the crude products. The crude product was triturated with excess hexanes for several times and removal of the solvents under reduced pressure afforded the Strecker product (α-aminonitriles) in almost analytically pure form (by NMR). The products were characterized by analyzing their spectral data and comparing them with those of the authentic samples (see supporting information, which is available from the authors, and ref. 10).