Total synthesis of the β-adrenergic receptor antagonist, the tetrahydroisoquinoline MY336-a and its epimer

The first total synthesis of the novel β-adrenergic receptor antagonist MY336-a 1 and its epimer 2 has been achieved from 2,3-dimethoxytoluene, by Jackson cyclisation of Nbenzyl-N-tosylamido acetals, Lewis acid-mediated addition of silicon-based nucleophiles to p-tosyliminium ions and base-catalysed epimerisation of 1-substituted hydroxytetrahydroisoquinolines, being key steps.