Enantioselectivity arylglycine synthesis

The enantioselective amination of iV-acyl oxazolidinones has been studied as part of a general approach to the synthesis of arylglycines. In this case, the enolization is initiated by a chiral magnesium bis(sulfonamide) complex. The oxazolidinone imide enolates are generated using catalytic conditions (10 mol% of magnesium complex) and treated in situ with BocN=NBoc to provide the corresponding hydrazide. 20 mol% of iV-methyl-p-toluensulfonamide are added to accelerate the reaction (equation 117). 

A catalytic approach to the synthesis of arylglycines was proposed by Evans and coworkers using enantioselective amination of iV-acy 1 oxazolidinones [54], Metallo-bis(sulfonamide) complexes derived from chiral diamines are potential chiral catalysts. The magnesium-bis(sulfonamide) complex 109 was generated by treating (S,S)-bis(sulfonamide) 108 with dimethylmagnesium in dichloromethane (Scheme 50). 

Apart from yielding arylglycines, chiral oxazolidinones also provide a powerful tool with which to stereoselectively fashion protected p-hydroxy tyrosines such as the C-ring building block 63. As indicated in Scheme 30, the critical element of this variant of substrate-controlled enantioselective synthesis is the inventive use... 

Wang, M.-X. and Lin, S.-J. (2001) Highly efficient and enantioselective synthesis of L-arylglycines and D-arylglycine amides from biotransformations of nitriles. Tetrahedron Lett., 42, 6925-6927. 

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