The synthesis of ‘tyrosyl’ peptidomimetics by acid-catalyzed N(1)–C(4) ring opening of 4-(4′-hydroxyphenyl)-azetidine-2-ones

Under acidic conditions, the N(1)–C(4) bond of 4-(4′-hydroxyphenyl)-azetidine-2-ones are cleaved with the formation of a stabilized benzylic carbocation intermediates. The intermediates were reduced by silanes or participated in intramolecular or intermolecular Friedel–Crafts reactions to produce tyrosine mimetics.