Synthesis, molecular structure and biological activity of bromobenzylgermatranes

The new series of benzylgermatranes RC6H4CH2Ge(OCH2CH2)(3)N, R = H (I), 2-Br (II), 3-Br (III), 4-Br (IV), has been obtained to study the influence of a substituent position on coordination of the germanium atom, the values of bond angles and neurotropic activity. Compounds I-IV were prepared by insertion of GeBr2 into carbon-bromine bond of the corresponding benzylbromide or bromo benzyl bromide in refluxing toluene, conversion of benzyl- or bromobenzyltribromogermanes into triethoxy derivatives by alcoholysis, and transalkoxylation with triethanolamine. The crystal structure of compounds I-IV was studied via the X-ray diffraction method. The intramolecular donor-acceptor bond N --> Ge in benzylgermatranes (2.175-2.219 Angstrom) is shorter than that in tolylgermatranes (2.212-2.230 Angstrom). Biological investigations have demonstrated that all benzylgermatranes (I-IV) are low toxic compounds (LD50 > 1000 mg kg(-1)) with high anaesthetic and anti-Corazol activity. Benzylgermatrane (1), 3-bromobenzylgermatrane (111) and 4-bromobenzylgermatrane (IV) improve memory processes and completely prevent animals from retrogradal amnesia (RA) caused by electroshock. (C) 2002 Elsevier Science B.V. All rights reserved.