Synthesis of 3-benzylisoquinolines by domino imination/cycloisomerisation of 2-propargylbenzaldehydes

An easy entry to uncommon 2-propargylbenzaldehydes was developed. 2-propargylbenzaldehydes demonstrated to be suitable building blocks for the synthesis of 3-benzyl isoquinolines by microwave promoted domino imination/cycloisomerisation in the presence of ammonium acetate. A small library of 3-benzyl isoquinolines was obtained in good yields under mild reaction conditions. Two alternative plausible reaction mechanisms are proposed.