Menthyl esters Reformatsky reaction

Reactions exhibiting diastereofacial selectivity, which occur when the imine or the enolate contains an endogenous stereocenter or a chiral auxiliary, have important applications for the synthesis of optically active 3-l ctams and 3-amino carboxylic acid derivatives. Early work by Furukawa et al. has demonstrated the viability of preparing optically active 3-amino acids from chiral imines. For example, the Schiff base derived from (5)-a-methylbenzylamine (110) reacts with Reformatsky reagent (111) to give, after hydrolysis and removal of the chiral auxiliary, 3-amino-2,2-dimethyl-3-phenylpropionic acid (112) in 33% ee (Scheme 21). Similar Reformatsky reactions have been performed using (-)-menthyl esters but the enantiomeric excess values are lower. ... 

Scheme 4.82 Rhodium catalyzed difluoro imine Reformatsky reaction of menthyl ester 378 for the synthesis of difluoro p-lactams 379.

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