A method for preparing a new class of protected amino intermediates is provided which utilizes reaction of an imido protected primary amine with a secondary amine. The intermediates thus provided are suitably protected for nucleophilic functionalization on the residue of the primary amine. The desired imido protected amine thus derivatized may be regenerated using acid. Further provided are methods for resolving racemic primary amines. Also provided are β-lactam intermediates protected with the new amino protecting group which are useful in the preparation of β-lactam antibiotics.