Silyl modification of biologically active compounds. 11. Synthesis, physico‐chemical and biological evaluation of N ‐(trialkoxysilylalkyl)tetrahydro(iso,silaiso) quinoline derivatives

N ‐(trialkoxysilylalkyl) derivatives of 1,2,3,4‐tetrahydroquinoline, 1,2,3,4‐tetrahydroisoquinoline and 4,4‐dimethyl‐4‐sila‐1,2,3,4‐tetrahydroisoquinoline were prepared and characterized by elemental analysis, 1 H, 13 C and 29 Si NMR spectroscopy. In vivo psychotropic properties and in vitro cytotoxic effects of 3‐[ N ‐(1,2,3,4‐tetrahydroisoquinolyl)]propyltriethoxysilane methiodide and 3‐[ N ‐(1,2,3,4‐tetrahydroisoquinolyl)]propylsilatrane are reported. Comparative study of 29 Si shifts in newly synthesized compounds suggested donor–acceptor interaction between nitrogen and silicon atom, which increased electron density at Si nuclei, revealing a stronger increment of N → Si transannular bond in comparison with N → Si α‐effect. The molecular structure of 3‐[ N ‐(1,2,3,4‐tetrahydroisoquinolyl)]propylsilatrane features a penta‐coordinate silicon atom having CSiO 3 pattern and Si…N intramolecular interaction. Copyright © 2005 John Wiley & Sons, Ltd.