Combretastatin-A2 (CA2), a potential anticancer drug in advanced preclinical development, is extracted from the medicinal plant Combretum caffrum. The NIR-FT Raman and FT-IR spectral studies of the molecule were carried out and ab initio calculations performed at the B3LYP/6-31G(d) level to derive the equilibrium geometry as well as the vibrational wavenumbers and intensities of the spectral bands. The vibrational analysis showed that the molecule has a similar geometry as that of cis-stilbene, and has undergone steric repulsion resulting in twisting of the phenyl ring with respect to the ethylenic plane. Vibrational analysis was used to investigate the lowering of the stretching modes, and enhancement of infrared band intensities of the C-H stretching modes of Me2 may be attributed to the electronic effects caused by back-donation and induction from the oxygen atom. Analysis of phenyl ring modes shows that the CA2 stretching mode 8 and the aromatic C-H in-planebending mode are equally active as strong bands in both IR and Raman spectra, which can be interpreted as the evidence of intramolecular charge transfer (ICT) between the OH and OCH 3 groups via conjugated ring path and is responsible for bioactivity of the molecule.

Vibrational spectral analysis of the novel non-linear optical (NLO) material, L-prolinium tartrate (LPT) was carried out using NIR-FT-Raman and FT-IR spectroscopy. The density functional theoretical (DFT) computations have been performed at B3LYP/6-31G (d) level to derive equilibrium geometry, vibrational wavenumbers, intensities and first hyperpolarizability. The reasonable NLO efficiency, predicted for the first time in this novel compound, has been confirmed by Kurtz-Perry powder second-harmonic generation (SHG) experiments. The charge-transfer interaction between the pyrrolidine ring and the carbonyl group of the tartrate anion through the intramolecular ionic hydrogen bonds is confirmed by the simultaneous activation of ring modes in IR and Raman spectra. The splitting of the ring-breathing mode, pseudorotational ring puckering modes and the NH 2 modes of the pyrrolidine ring lead to the conclusion that the pyrrolidine ring adopts a conformation intermediate between the envelope (bent) form and the half-chair (twisted) form, resulting in the lowering of symmetry fromC 2 to C s . The lowering of the methylenic stretching wavenumbers and the enhancement of the stretching intensities suggest the existence of the electronic effects of back-donation in LPT. The positional disorder of the pyrrolidine ring, the presence of blue-shifting H-bonds as well as other non-bonded interactions in LPT, low frequency H-bond vibrations and the role of intramolecular charge transfer and the hydrogen bonds in making the molecule NLO active have been analysed on the basis of the vibrational spectral features.

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Substituted quinolines 4, S, and 9 were reported from o-allyl ethers of cyclohexanone derivatives by [2,3] sigmatropic rearrangement followed by cyclization. All the new compounds were characterized by 1R and 'H NMR spectra.Brought to you by | Purdue University Libraries Authenticated Download Date | 5/29/15 7:32 PM Vol. 7, No. 5, 2001 Cyclohexanone derivatives: synthons for substituted quinolines ExperimentalMelting points were determined in open capillaries on Tempo Mel-Temp apparatus and arc uncorrected. The purity of the compounds was checked by thin layer chromatography (silica gel-G, BDH), pet. ether (40-60°C): ethyl acetate (3:1) as eluents). The 1R spectra were recorded on a Perkin-Elmer Infrared spectrometer (v nux in cm" 1 ) model 337 in KBr pellets. The 'H NMR spectra were recorded in CDC1, 200 MHz on Bruker spectrospin and Varian LiM-360 spectrometers with TMS as an internal standard (Chemical shifts in δ ppm).Microanalyses were performed by Microanalytical laboratory, University of Pune, Pune, India.3,5-Diaryl-2-cyclohexenone (1) and 3,5-diarylcyclohexanone (6) were prepared according to literature procedures. 7 ' 8 Preparation of Oxime of 3,5-diaryl-2-cyclohexenone (2a-c) / 3,5-diaryl-cycIohexanone (7a-c)Λ solution of 3,5-diarylcyclohexenone (2) / 3,5-diarylcyclohexanone (6) (0.01 mol), hydroxylamine hydrochloride (0.69 g, 0.012 mol) and a catalytic amount of triethylamine in ethanol was refluxed on a water bath for 1-2 hrs. The contents were concentrated and cooled The product separated was filtered and dried. It was recrystallized from ethanol to gel pure 2/7. Preparation of O-allyl ether of 3,5-diaryl-2-cycIohexenone oxime (3a-c)/ 3,5-diarylcycIohexanone oxime (8 a-c).A mixture of 2/7 (0.01 mol) and allyl bromide (1.43 g, 0.02 mol) in methanol was cooled at ice-salt bath temperature. To this, a solution of sodium hydroxide (3 g) in methanol (60 mi) was added and refluxed for 3-4 hrs. The reaction mixture was cooled, the precipitated NaBr was removed by filtration and the filtrate was concentrated. The resultant viscous mass was solidified by heating with hexane and filtered through a column of silica gel to obtain pure 3/8. Preparation of 5,6-dihydro-5,7-diarylquinoIine (4a-c) / 5,6,7,8-tetrahydro-5,7-diaryl- quinoline (9a-c)A solution of 3/8 (0.003 mol) in dry benzene (10 ml) was taken in a pyrex sealed tube under nitrogen atmosphere and heated at 200°C in an oil bath for two days. It was cooled and opened. The contents were transfered and benzene was removed under reduced pressure. The semi-solid obtained was subjected to column chromatography to get pure 4/9. Preparation of 5,7-diaryiquinoline (5a-c).A 1:1.5 molar mixture of 4/9 and DDQ in dry benzene (20 ml) was heated at reflux temperature for 2 hrs under nitrogen atmosphere. The precipitated DDQ-H 2 was filtered off Brought to you by | Purdue University Libraries

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