The SRN1 reaction between o-halogeno-benzylamines and enolates derived from a series of ketones and aldehydes affords 1, 2 dihydro-isoquinolines from which are obtained (i) the isoquinoline derivatives, either spontaneously or by treatment on Pd-C and (ii) the 1, 2, 3, 4 tetrahydro-isoquinoline derivatives after sodium borohydride reduction.