Results 191 to 200 of about 13,031 (233)

Synthesis of tetrasubstituted pyrazines and pyrazine N-oxides

Tetrahedron Letters, 2010
Abstract An efficient synthesis of tetrasubstituted unsymmetrical pyrazines and their related pyrazine N-oxides has been developed from commercially available 2-chloro-3-methylpyrazine. The procedure and scope of these synthesis routes are described.
Jae Uk Jeong, Xiaoyang Dong, Attiq Rahman, Robert W. Marquis   +3 more
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2,3,5,6-Tetrakis(phenoxymethyl)pyrazine and 2,3,5,6-tetrakis(phenylsulfanylmethyl)pyrazine

Acta Crystallographica Section C Crystal Structure Communications, 2007
The title compounds, C(32)H(28)N(2)O(4), (I), and C(32)H(28)N(2)S(4), (II), respectively, are tetrasubstituted pyrazines and both possess C(i) symmetry. They differ only in the hetero atom (X) of the -CH(2)XPh side-arm substituents: X = O in (I) and S in (II).
Assoumatine T, Gasser G, Stoeckli-Evans H   +2 more
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Pyrazines

ChemInform, 2005
AbstractFor Abstract see ChemInform Abstract in Full Text.
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Pyrazine chemistry. Part 9. Oxygenation of pyrazines and pyrimidines

Journal of the Chemical Society, Perkin Transactions 1, 1979
Singlet oxygen adds to certain substituted pyrazines and pyrimidines to form the endo-peroxides in high yield. The peroxides derived from the pyrazines are often stable compounds. 2,5-Diethoxy-3,6-dimethyl-3,6-epidioxy-3,6-dihydropyrazine can be reduced to the corresponding diol with sodium borohydride, whilst the parent pyrazine is regenerated by ...
Janet L. Markham, Peter G. Sammes
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Vapour and crystal spectra in polarized light of pyrazine-d0, cis pyrazine-d2 and pyrazine-d4

Spectrochimica Acta, 1964
Abstract The infrared spectra of pyrazine-d0, cis pyrazine-d2 and pyrazine-d4 have been measured between 4000 and 400 cm−1. The spectra have been obtained in the vapour and solid states. The dichroic behaviour of the bands has been measured on polycrystalline fully oriented samples.
S. Califano, G. Adembri, G. Sbrana
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ChemInform Abstract: Pyrazine. Syntheses of Naturally Occurring Pyrazines

ChemInform, 1997
AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
A. OHTA, Y. AOYAGI
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Pyrazines in foods

C R C Critical Reviews in Food Technology, 1973
Because of their unique organoleptic properties, pyrazine compounds have recently been receiving increased attention in food related areas. Numerous compounds have been detected in foods, and others have been synthesized and promoted as flavoring agents. This review provides the reader with a composite appreciation of pyrazines in foods. A total of ten
Joseph A. Maga, Charles E. Sizer, D. V. Myhre   +2 more
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Pyrazines: occurrence, formation and biodegradation

Applied Microbiology and Biotechnology, 2009
Pyrazines are a class of compounds that occur almost ubiquitously in nature. Pyrazines can be synthesised chemically or biologically, and are used as flavouring additives. The major formation of pyrazines occurs during heating of food. There is very little information available on the degradation of these compounds. In humans and animals, pyrazines are
Rudolf, Müller, Sugima, Rappert
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Mass-Analyzed-Threshold-Ionization-Spectroscopy of Pyrazine and Pyrazine-Ar

Zeitschrift für Physikalische Chemie, 2007
Vibrational spectra of the pyrazine and the pyrazine-Ar cation in the electronic ground state (D 0) have been measured via several intermediate states of the first excited state (S 1) by mass-analyzed threshold ionization spectroscopy.
Mikko Riese, Angela Gaber, Jürgen Grotemeyer   +2 more
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Experiments on the synthesis of pyrazine nucleosides

Journal of the Chemical Society, Perkin Transactions 1, 1975
Pyrazine nucleosides were prepared by condensation of acylglycosyl halides with trimethylsilyloxypyrazines in benzene in the presence of silver perchlorate. Reaction of 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide (1) with 2,3-bis(trimethylsilyloxy)pyrazine (2) gave 1,4-dihydro-1,4-bis-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl) pyrazine-2,3-dione
G W, Cheeseman, A J, Freestone, R A, Godwin, T L, Hough   +3 more
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