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1.
The 1H and 13C nmr spectra of 11,12-dimethoxy[1]benzothieno[3,2-a]-4,7-phenanthroline and its 8-chloro precursor were totally assigned using a combination of two-dimensional nmr techniques. After correlation of the majority of the proton signals by a COSY spectrum and one-bond heteronuclear correlation, the full assignment of the 1H and 13C nmr spectra of the novel heterocyclic compounds required the application of long-range CH coupling information particularly for quaternary carbon resonance assignments and the orientations of individual spin systems relative to one another. Key long-range heteronuclear couplings in both compounds served to confirm the one-bond heteronuclear correlations. Unequivocal interpretation of the spectral data leads to the complete assignments of the resonances. 相似文献
2.
Andrew S. Zektzer Gary E. Martin Raymond N. Castle 《Journal of heterocyclic chemistry》1987,24(3):879-884
Phenanthro[3,4:3′,4′]phenanthro[2,1-b]thiophene ( 1 ) served as the model system to evaluate two-dimensional proton zero quantum coherence nmr in order to establish the vicinal proton-proton connectivities. The utility of the two-dimensional proton zero quantum nmr experiment has been compared with the utility of the traditional autocorrelated proton-proton (COSY) experiment. In the case of a molecule such as 1 , where the proton chemical shifts are so highly congested, the zero quantum coherence experiment provides data not obtainable from the COSY experiment. 相似文献
3.
Jiann-Kuan Luo Kazufumi Takahashi J. Dew Mckenney Raymond N. Castle Milton L. Lee 《Journal of heterocyclic chemistry》1989,26(6):1845-1848
The synthesis of 2-naphthyl 2′-dibenzothienyl ether, 1-(1′-naphthyl)-2-(4″-acridinyl)ethane and a series of naphthylethyldibenzothiophenes is reported. 相似文献
4.
Kazufumi Takahashi Raymond N. Castle Milton L. Lee 《Journal of heterocyclic chemistry》1987,24(4):977-979
The four acridinecarbaldehydes, namely, acridine-1-carbaldehyde, acridine-2-carbaldehyde, acridine-3-carbaldehyde, and acridine-4-carbaldehyde have been synthesized for the first time. 相似文献
5.
Inverted and suppressed direct response HMQC-TOCSY spectra - a convenient method of spectral editing
Gary E. Martin Timothy D. Spitzer Ronald C. Crouch Jiann-Kuan Luo Raymond N. Castle 《Journal of heterocyclic chemistry》1992,29(2):577-582
HMQC-TOCSY spectra provide a convenient means of establishing proton-proton connectivities in congested spectra of complex aromatic heterocycles. Advantage is taken of the greater dispersion of the 13C nmr spectrum to circumvent overlap which would preclude spectral interpretation through the usual COSY spectrum. A recently reported method for inverting direct responses (IDR) in HMQC-TOCSY spectra is demonstrated for [1]benzothieno[2,3-c]naphtho[2,1-g]quinoline. A modification of the IDR-HMQC-TOCSY method is also demonstrated which is capable of fully suppressing direct responses (SDR) without resorting to the timing of the onset of decoupling as in the original report of the HMQC-TOCSY experiment. SDR-HMQC-TOCSY has the further advantage of allowing the use of higher levels of digitization in F2 than can be attained when broadband heteronuclear decoupling is employed. 相似文献
6.
Six proficiency tests have now been completed in an ongoing program of the UK Food Analysis Performance Assessment Scheme (FAPAS) for the analysis of acrylamide in a range of food matrixes. Homogeneous test material samples were requested by laboratories throughout the world, with 29 to 45 submitting results for each test. Results were analyzed by appropriate statistical procedures, and z-scores were awarded for reported values. In the absence of both legislation and collaborative trial data, the target standard deviation was derived from the Horwitz equation, although it is acknowledged that there is a need to establish a "fit for purpose" target standard deviation specifically for acrylamide analysis. Participants were encouraged to use the analytical method routinely used in their own laboratory and to provide details of their procedure. Close examination of the data submitted indicates that performance is generally acceptable in terms of accuracy. There is no significant difference between results submitted by gas chromatography and liquid chromatography (GC and LC) methods, and no method dependency on the use of internal standards or sample size. However, choice of extraction solvent may be important, with indications that plain water is an acceptable extraction method. There is evidence from the most recent test that direct (underivatized) GC methodology may present problems, but more data are required and this aspect will be monitored in the continuing proficiency testing program. 相似文献
7.
8-Amino-s-triazolo[4, 3-b]pyridazine (I), an adenine analog has been prepared by two different routes. Likewise 8-amino-3-phenyl-s-triazolo[4,3-b]pyridazine (V) has been prepared. Both of these compounds have been prepared utilizing 3,4,5-trichloropyridazine and 3,4,6-trichloropyridazine as the starting materials thus interrelating the 3,4,5-and the 3,4,6-series. A variety of other transformations have been carried out. 相似文献
8.
Jiann-Kuan Luo Andrew S. Zektzer Raymond N. Castle Ronald C. Crouch John P. Shockcor Gary E. Martin 《Journal of heterocyclic chemistry》1993,30(2):453-460
Two novel heterocyclic ring systems, namely, [1]benzothieno[2,3-c]naphtho[1,2-f]quinoline and [1]benzothieno[2,3-c]naphtho[2,1-g]quinoline have been synthesized and characterized by inverse detected two-dimensional nmr methods. Unequivocal total assignments of the proton and carbon nmr spectra were made through the concerted utilization of HMQC (Heteronuclear Multiple Quantum Correlation) and a combination of HMBC (Heteronuclear Multiple Bond Correlation) and HMQC-TOCSY (HMQC with proton TOtal Correlation Spectroscopy). 相似文献
9.
M. J. Musmar M. Robert Willcott Gary E. Martin Robert T. Gampe Masatomo Iwao Milton L. Lee Ralph E. Hurd Leroy F. Johnson Raymond N. Castle 《Journal of heterocyclic chemistry》1983,20(6):1661-1669
Development of successively higher field nmr spectrometers has facilitated the study of increasingly more complex molecules, although smaller molecules such as phenanthro[3,4-b]thiophene still offer very substantial assignment problems because of the highly congested nature of their 1H- and 13C-nmr spectra. Assignments of such spectra, if they are to be unequivocal, frequently require the utilization of two-dimensional nmr spectroscopic techniques. Total assignments of the 1H- and 13C-nmr spectra of phenanthro[3,4-b]thiophene are reported. Assignments were based on a conventional high resolution 500 MHz 1H-nmr spectrum, autocorrelated two-dimensional 1H-nmr spectra (COSY), two-dimensional 1H-13C chemical shift correlation spectra and a modified version of autocorrelated 13C-13C double quantum coherence two-dimensional nmr spectroscopy. From NOE measurements, a separation of 1.99 Å between H1 and H11 was computed, suggesting that phenanthro[3,4-b]thiophene has a pronounced helical conformation in solution. 相似文献
10.
Hirotaka Kudo Marvin L. Tedjamulia Raymond N. Castle Milton L. Lee 《Journal of heterocyclic chemistry》1984,21(6):1833-1839
The synthesis of phenanthro[1,2-c]dibenzothiophene (6) , phenanthro[4,3-c]dibenzothiophene (10) , phenanthro[2,1-a]dibenzothiophene (14) , phenanthro[3,4-a]dibenzothiophene (16) , phenanthro[1,2-a]dibenzothiophene (19) , phenanthro[2,1-b]dibenzothiophene (20) , 8-methylphenanthro[3,2-a]dibenzothiophene (24) , 7-methylphenanthro[1,2-a]dibenzothiophene (25) , phenanthro[3,4-a]dibenzothiophene (27) , phenanthro[4,3-a]-dibenzothiophene (28) , 6-methylphenanthro[2,3-a]dibenzothiophene (31) , and 5-methylphenanthro[4,3-a]dibenzothiophene (32) is described. 相似文献