Synthesis of enantiomerically and diastereomerically pure 2(S)-amino-6(R)-hydroxy-1,7-heptanedioic acid dimethyl ester hydrochloride from cycloheptadiene.

The complete carbon framework of enantiomerically and diastereomerically pure 2(S)-amino-6(R)-hydroxy-1,7-heptanedioic acid dimethyl ester hydrochloride was derived from cycloheptadiene in six steps utilizing an amino acid-derived acylnitroso Diels-Alder reaction as the key step. This versatile amino diester has been previously used to synthesize amino-differentiated diaminopimelic acid (DAP) and biologically active analogues. In addition, after formation of a novel aminoxy diketopiperazine, the newly formed carboxyl groups were differentiated by a novel transpeptidation of the amino acid that directed the stereochemistry of the initial cycloaddition.