Syntheses, structures and spectroscopy of polychlorinated dihydrocamphenes. An experimental and theoretical study

Issue in Honor of Professor Kalevi Pihlaja ARKIVOC 2001 (iii) 95-113 Syntheses, structures and spectroscopy of polychlorinated dihydrocamphenes. An experimental and theoretical study Jari J. Koivisto,*a Erkki T. Kolehmainen,a Vladimir A. Nikiforov,b Maija J. Nissinen, a Kari A. Tuppurainen,c Mikael Peräkylä,c Sergei A. Miltsov,b and Vladimir S. Karavanb a Department of Chemistry, University of Jyväskylä, P.O. Box 35, FIN-40351 Jyväskylä, Finland b Institute of Chemistry, Laboratory of Physical Organic Chemistry, University of St.Petersburg, Universitetskii pr. 2, 198904 St. Petersburg, Russia c Department of Chemistry, University of Kuopio, Snellmania, Savilahdentie 9 E, 70210 Kuopio, Finland E-mail: M.Sc. Jari Koivisto: jarkoiv@cc.jyu.fi, Prof. Erkki Kolehmainen: ekolehma@cc.jyu.fi, Dr. Vladimir Nikiforov: vn2076@vn2076.spb.edu, Lic.Phil. Maija Nissinen: majoni@cc.jyu.fi, Dr. Kari Tuppurainen: Kari.Tuppurainen@uku.fi, Dr. Mikael Peräkylä: Mikael.Perakyla@uku.fi, Dr. Sergei Miltsov: dm@sm2159.spb.edu, and Dr.Vladimir Karavan: vn2076@vn2076.spb.edu *The author to whom the correspondence should be addressed: M.Sc. Jari Koivisto, Department of Chemistry, University of Jyväskylä, P.O. Box 35, FIN-40351 Jyväskylä, Finland E-mail: jarkoiv@cc.jyu.fi (received 30 Sep 00; accepted 01 Jan 99; published on the web 20 May 02) Abstract Nine novel polychlorinated dihydrocamphenes (1-9) have been isolated from reaction mixtures obtained by the chlorination of lower chlorinated monoterpenes. These compounds are potential congeners of insecticide toxaphene. The 1H and 13C NMR spectra of 1-9 have been assigned by means of 1H,1H DQF COSY (double-quantum filtered correlation spectroscopy), 1H,1H ROESY (rotating frame nuclear Overhauser effect spectroscopy), PFG 1H,13C HMQC (pulsed field gradient heteronuclear multiple quantum coherence), 1H,13C HMBC (heteronuclear multiple bond correlation) experiments, and computer aided 1H NMR spectral analysis. In the case of 2, the structure has been determined by X-ray methods. Full geometry optimizations have been performed at the ab initio HF/6-31G* level for a comparison with the conformational and structural properties obtained from the NMR- and X-ray experiments. The optimized geometries are in excellent agreement with the experimental structures. In addition, rotation barriers of compounds 7 and 9 have been characterized with the semiempirical AM1 method. The gauge-including atomic orbital (GIAO) method have been employed to calculate 13C chemical shifts of 1-9 using density functional theory (DFT) at the B3LYP/6-311G* level and the HF/6-31G* optimized structures as geometry input. A comparison of the calculated and experimental data yielded a regression equation, which with added indicator variable (the number of chlorine atoms attached to each carbon) is capable of the accurate prediction of carbon chemical shifts for these compounds. Keywords: 1D/2D NMR, ab initio, AM1, conformation, DFT, GIAO, MO calculations, polychlorinated dihydrocamphenes, stereochemistry, toxaphene, X-ray structure. ISSN 1424-6376 Page 95 ©ARKAT USA, Inc 0