An approach to chiral amino acids via reductive amination of ketones: hydride reduction of 1-(S)-phenethyl amine derived Schiff bases of C-protected alpha-keto acids

作者：Chandrasekhar Sosale^*; Rao V Mohana

来源：Tetrahedron: Asymmetry , 2012, 23(13): 1005-1009.

DOI：10.1016/j.tetasy.2012.06.017

Various 1-acyl-2,4,10-trioxaadamantanes were prepared from the corresponding 1-methoxycarbonyl derivatives, via conversion to the N-acylpiperidine derivatives followed by reaction with a Grignard reagent in refluxing THF. These alpha-keto orthoformates were converted to the corresponding imines with 1-(S)-phenethyl amine (TiCl4/Et3N/toluene/reflux), with the Schiff bases being reduced further with NaBH4 (MeOH/0 degrees C) into the corresponding 1-(S)-phenethyl amines (diastereomeric excess 91:9 by NMR). Hydrogenolysis of the phenethyl group (Pd-C/MeOH) finally led to the 1-(aminoalkyl)trioxaadamantanes, which are chiral C-protected alpha-amino acids, in excellent overall yields.

• 出版日期2012-7-15