Seebach’s self-regeneration

Pattenden s synthesis of (/ )- and (S )-2-methyl-cysteine [12] is based on Seebach s self regeneration of chirality [13]. Scheme 5 shows the synthesis of the (/ )-isomer 5b. 

Table 3.1. Selected examples of Seebach s self-regeneration of chirality centers (Scheme 3.9)...

In the literature, a variety of methodologies have been reported for the asymmetric synthesis of quaternary a-amino acids. [3] Among these methods, Seebach s self-regeneration of stereocenters [5] for the preparation of a-substituted amino acid derivatives (Scheme 3) was most attractive to us. The principal reasons are the ready availability of the required chiral imidazolidinones (up to 90% ds), the stability of the corresponding enolates at higher temperature (up to 0 C), and the predictability of the stereochemical outcome. 

The application of self-regeneration of chirality to oxazohdinones and imi-dazolidinones 110 (A = protected N, B = 0 or NMe, respectively) became well known as Seebach s amino acid synthesis. Despite the elegancy of this approach. 

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