Practical asymmetric syntheses of all four 2,3-methanoleucine stereoisomers

Article abstract of DOI:10.1016/0040-4039(95)00382-M

All four stereoisomers of the 2,3-methanoamino acids BOC-E-cyclo-Leu and BOC-Z-cyclo-Leu were prepared from the optically active diol 4 (and its enantiomer) derived from valine. The challenges associated with introduction protected amine functionalities cis to the side chain were overcome by using the vinylogous malonate synthon, dimethyl gluconate.