Hydantoins stereochemistry

Other rigid cyclopentanones thus far studied have been ( )-camphor and ( )-norcamphor. The stereochemistry of the reactions confirms Edward s rule. While ( )-norcamphor gives, by the Bucherer-Bergs method, the hydantoin with the C-4 carbonyl group in the exo position,81 ( + )-camphor gives the hydantoin with an endo C-4 carbonyl group.82 These are, respectively, the more accessible sides.83,84... 

The other major class of cyclic amino acid derivative used in dynamic resolution reactions is the hydantoin group. Like oxazolinones, hydantoins readily undergo racemisation under mild conditions. Systems involving a two step procedure using D-hydantoinase and a carbamoylase were reported to provide a route to D-amino acids[S2, 53). Dynamic resolution of a p-hydroxyphenyl substituted hydantoin was reported in 1987[541. Using the intact cells of Pseudomonas sp. AJ-11220, the amino acid was prepared in over 90% yield, as shown in Fig. 9-24. This hydrolytic procedure leads directly to the amino acid, and the same enantiomer of product, the D-amino acid, was obtained independently of the stereochemistry of the substrate. 

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