Conformational analysis. 50. C-Methyl-1,2,3,4-ttrahydroisoquinolines

摘要

Conformational equilibria in 1-, 3-, and 4-methyl-1,2,3,4-tetrahydroisoquinolines (THIQs) and the diastereomeric pairs of their 1,3- nd 1,4-dimethyl homologs have been determined by mesurement of H_3/H_4(trans) coupling constants and have been confirmed by molecular mechanics [MMP2(85)] calculations. The experimental -ΔG° values (a→e) for the monomethyl compounds (computed values in parentheses) in kcal mol~1 are Me~1, 0.56 (0.46); Me-3, 1.63 (1.53); and Me-4, -0.19 (-0.34); Me-3, 1.15 (1.46); and Me-4, 0.35 (0.10) kcal mol~1.