Studies on 1, 2, 3, 4-Tetrahydroisoquinolines. IV. β-Adrenoceptor Activity and Absolute Stereochemistry of (-)-5, 7-Dihydroxy-1-(3, 4, 5-trimethoxybenzyl)-1, 2, 3, 4-tetrahydroisoquinoline

Racemic 5, 7-dihydroxy-1-(3, 4, 5-trimethoxybenzyl)-1, 2, 3, 4-tetrahydroisoquinoline [(±) -1], a positional isomer of trimetoquinol (TMQ) with respect to its dihydroxy moiety, has been optically resolved. The bronchodilating activity in anesthetized cats (i.v. administration) was found to reside in the levorotatory enantiomer [(-) -1]. The absolute stereochemistry of the active enantiomer [(-) -1] was determined to be S by X-ray crystallographic analysis.