Recent advances in the C(1)-functionalization of tetrahydroisoquinolines via multicomponent reactions

1,2,3,4-Tetrahydroisoquinoline is an important structural motif of various natural products and therapeutic lead compounds. In recent years, considerable research interest has been witnessed toward synthesis of its C(1)-substituted derivatives, since they can act as precursors for various alkaloids displaying multifarious biological activities. This minireview offers short and non-exhaustive epitome of various multicomponent reactions for the C(1)-functionalization of 1,2,3,4-tetrahydroisoquinolines. In particular, reactions involving isomerization of iminium intermediate (exo/endo isomerization) are highlighted for the period of 2013–2019.