DETERMINATION OF RING CONFORMATION IN 1-BENZYL-1,2,3,4-TETRAHYDROISOQUINOLINES AND A NEW SYNTHESIS OF THE CHIRAL COMPOUNDS

The conformation of the piperideine ring in 1-benzyl-1,2,3,4-tetrahydr oisoquinolines was determined as H-2(3) form with a pseudoaxial positi on of the 1-benzyl group by circular dichroism (CD) spectral compariso n,vith 1-methyl-1,2,3,4-tetrahydroisoquinolines The chiral center at C -1 of 1,2,3,4-tetrahydroisoquinoline (TIQ) was constructed in an unamb iguous manner by applying a new method of TIQ synthesis utilizing the Pummerer reaction as a key step, Enantiomerically pure (R)- and (S)-1- methyl- and 1-benzyltetrahydroisoquinolines (1) were prepared starting from readily available chiral amines (2) in good overall yields.