Determination of ring conformation in 1-benzyl-1,2,3,4- tetrahydroisoquinolines and a new synthesis of the chiral compounds

Article abstract of DOI:10.1248/cpb.46.430

The conformation of the piperideine ring in 1-benzyl-1,2,3,4- tetrahydroisoquinolines was determined as ²H₃ form with a pseudoaxial position of the 1-benzyl group by circular dichroism (CD) spectral comparison with 1-methyl-1,2,3,4-tetrahydroisoquinolines. The chiral center at C-1 of 1,2,3,4-tetrahydroisoquinoline (TIQ) was constructed in an unambiguous 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.