Synthesis, spectral

Elemental abundances were determined by spectral synthesis of individual lines, compared to observed spectra obtained with the FEROS spectrograph at the ESO-1.5m telescope. 

Abstract. Oxygen abundances of a large number of metal-rich stars, with and without known planets, were derived from the forbidden line [OI] 6300 A, the OI 7771-5 A triplet and from near-UV OH lines. Non-LTE corrections were calculated and applied to the LTE abundance results derived from the OI 7771-5 A triplet. Spectral synthesis was performed for several OH lines. Results from different indicators are compared. We study abundance trends in planet host and comparison sample stars. We find for all the indicators that, on average, [O/Fe] clearly decreases with [Fe/H], with significantly negative slopes in all the linear fits. 

Mass Spectra and Retro-Mass Spectral Synthesis... 

Mass Spectra and the Retro-Mass Spectral synthesis.65... 

Hesse s excellent general introduction to alkaloid chemistry naturally contains numerous references to indole alkaloids, and in particular contains a detailed discussion of the structure elucidation of villalstonine, by way of illustration of modern experimental methods used in alkaloid chemistry.1 Indole alkaloids also receive mention in a brief review of hypotensive principles from plants,20 in a review of synthesis via photocyclization of enamides,2 and in another on the use of lactones in alkaloid synthesis.21 Kametani has also reviewed (unfortunately, in Japanese) the synthesis, by his group, of alkaloids by retro mass spectral synthesis .2d The proceedings of the 1979 meeting of the Phytochemical Society of Europe, which were entirely devoted to indole alkaloids, are now available.3... 

The Kametani group further investigated quinazolone synthesis by cycloaddition of iminoketene with imines based on the concept of retro mass spectral synthesis and applied it to the total syntheses of deoxyvasicinone (24),... 

This paper reports a study to verify the relationship between functional group distribution and thermal decomposition behavior. A Fourier transform infrared spectrometer (FTIR) has been employed to obtain quantitative infrared spectra of the coals, chars, and tars produced in the devolatilization experiments. The spectra have been deconvoluted by using a computerized spectral synthesis routine to obtain functional group distributions, which are compared to the model parameters. 

A new and very neat synthesis of evodiamine and rutaecarpine is described by the authors as a retro mass spectral synthesis , since the original conception was derived from the mode of fragmentation of these alkaloids in the mass spectrometer this involves a familiar retro Diels-Alder fission of ring c. Evodiamine (16a) was thus constructed by a 27r + 47r cycloaddition of 3,4-dihydro-/8-carboline with the keteneimine (17), prepared in situ by elimination of sulphur dioxide from the sulphinamide anhydride (18) (Scheme 7). When the anthranilic acid derivative (19) was used the product was rutaecarpine (20) itself, the initially formed dihydro-... 

Kametani, T., 8c Fukumoto, K. 1976. "Total Synthesis of Natural Products by Retro Mass Spectral Synthesis." Accounts of Chemical Research, 9 319-325. 

Spectral Synthesis Much previous work has been done to identify the functional groups responsible for the observed peaks Extensive references may be found in Lowry, (1 ), and van Krevelen ( ) A convenient way to obtain areas under the absorbance peaks is to use a curve analysis program to synthesize the IR spectra... 

The above analysis was applied to a wider group of coals (including 44 coals from the Exxon Library and a number of coals from the Pennsylvania State University coal bank) and several sets of chars, tars and recycle solvents. Several improvements were also made in the spectral synthesis routine. 

Kametani et al have achieved a very neat synthesis of euxylophoricine A (20) by application of their retro-mass-spectral synthesis. Cycloaddition of 3,4-dihydro-j8-carboline with the iminoketen (21b), prepared in situ by decomposition of the sulphinamide anhydride (21a), gave euxylophoricine A (20) directly. Euxylophoricine C (22) was prepared by an exactly analogous route (Scheme 4). 

By careful selection of the component frequencies and index of modulation, and by combining multiple carrier/modulator pairs, many spectra can be approximated using FM. The amplitudes and phases (described by Bessel functions) of the individual components cannot be independently controlled, however, so FM is not a truly generic waveform or spectral synthesis method. Since the very definition of FM is a nonlinear function transformation. 

Kametani, T., T. Higa, C. V. Loc, M. Ihara, M. Koizumi, and K. Fukumoto Iminoketene Cycloaddition. 1. A Facile Synthesis of Quinazolone System by Condensation of Iminoketene with Imines — A Total Synthesis of Evodiamine and Rutaecarpine by Retro Mass-Spectral Synthesis. J. Amer. Chem. Soc. 98, 6186 (1976). 

---