Organic Letters 2001-04-19

Asymmetric strecker synthesis of alpha-amino acids via a crystallization-induced asymmetric transformation using (R)-phenylglycine amide as chiral auxiliary.

W H Boesten, J P Seerden, B de Lange, H J Dielemans, H L Elsenberg, B Kaptein, H M Moody, R M Kellogg, Q B Broxterman

Index: Org. Lett. 3(8) , 1121-4, (2001)

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Abstract

[reaction: see text]. Diastereoselective Strecker reactions based on (R)-phenylglycine amide as chiral auxiliary are reported. The Strecker reaction is accompanied by an in situ crystallization-induced asymmetric transformation, whereby one diastereomer selectively precipitates and can be isolated in 76-93% yield and dr > 99/1. The diastereomerically pure alpha-amino nitrile obtained from pivaldehyde (R1 = t-Bu, R2 = H) was converted in three steps to (S)-tert-leucine in 73% yield and >98% ee.