β-Lactam-synthon-interceded diastereoselective synthesis of novel thioxo-imidazolines: a convenient access to functionally decorated 4,5-dihydro-imidazoles

The manuscript describes a facile synthesis of an equimolar diastereomeric mixture of 2-thioxo-imidazolines via β-lactam synthon approach using racemic N-aryl β-lactams. The diastereoselectivity in the reaction has been introduced by initially synthesizing 3-isothiocyanato-β-lactams with methoxide assisted amidolysis and intramolecular cyclization. The synthesized diastereoselective trans-2-thioxo-imidazolines were easily converted into diversely functionalized 4,5-dihydro-imidazoles through usual synthetic transformations without the aid of any protic or Lewis acid conditions.