Synthesis of Piperazines. VIII

Ishiguro, Takeo; Matsumura, Masaki

doi:10.1248/yakushi1947.78.3_229

Cited by 17 publications

(10 citation statements)

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“…2,3-Dihydropyrazine derivatives have assumed great importance as flavorants 30 and in medicine field, where they are used for their DNA strand-breaking activity, 31 which may be related to the apoptotic activity of amino sugars, 32 and also for their biological 33 and cyclooxygenase inhibitory 34 activity. 2,3-Dihydropyrazines are generally prepared by the procedure of Ishiguro 35 from ethylenediamine and a diketone in diethyl ether. Another synthesis was performed starting from diketones and diamino compounds in refluxing benzene.…”

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A Green Synthesis of Quinoxalines and 2,3-Dihydropyrazines

Delpivo¹,

Micheletti²,

Boga³

2013

Synthesis

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Quinoxaline and dihydropyrazine derivatives were obtained in high yields by simple addition of 1,2-diamines and 1,2-dicarbonyl compounds in water. In some cases, the products spontaneously precipitated from the reaction mixture, making it possible to recover and reuse the mother liquor for further condensations. The very mild reaction conditions, the high yields of the products, and the absence of any catalyst make this methodology an efficient and green route to quinoxalines and dihydropyrazines.

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A Green Synthesis of Quinoxalines and 2,3-Dihydropyrazines

Delpivo¹,

Micheletti²,

Boga³

2013

Synthesis

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“…I were obtained from commercial sources. Of those listed in Tables II, III, and IV, pyridine, pyrazine, methylpyrazine, and 2,5-dimethylpyrazine were available commercially; the remainder were synthesized according to known procedures (Behun and Levine, 1961;Ishiguro and Matsumura, 1958;Kamal and Levine, 1962;Kipping, 1929;Klein and Spoerri, 1951).…”

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Steam volatile components of roasted barley

Collins¹

1971

J. Agric. Food Chem.

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Gas-liquid chromatography was used to examine the steam-volatile fraction of roasted barley. Ethanal, propanal,* 2-methylpropanal, 2-methylbutanal, 3methylbutanal, pentanal,* hexanal,* furfural, propanone, butanone, 2,3-butanedione,* 2,3-pentanedione, ethanol,* and pentanol* were identified in the headspace. Pyridine, pyrazine,* methylpyrazine, 2,5-dimethylpyrazine, 2,3-dimethylpyrazine,* trimethylpyrazine, 2-ethyl-3-methylpyrazine,* 2-ethyl-5-methylpyrazine, 2,5-dimethyl-3-ethylpyrazine,* and 3,5-dimethyl-2-ethylpyrazine* were found in the basic fraction. Flavor aspects are discussed. The compounds with an asterisk have not previously been reported as present in roasted barley.Roasted barley is sometimes used to provide the desired color in dark beers.

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“…1,27) The ketenes (2a-c) were also synthesized by established methods. 28,29) General Procedure A solution of methoxyacetyl chloride (0.43 g, 4 mmol) in CH 2 Cl 2 (5.5 ml) was added dropwise to a solution of 2,3-dihydropyrazine derivative (2 mmol) in CH 2 Cl 2 (7.0 ml) containing triethylamine (0.55 ml).…”

Section: Methodsmentioning

confidence: 99%

Chemical Reactivity of Dihydropyrazine Derivatives. Cycloaddition Behavior toward Ketenes

Nakahara

Yamaguchi

Yoshitake

et al. 2009

CHEMICAL & PHARMACEUTICAL BULLETIN

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Dihydropyrazines (DHPs), which are derived from aminosugars, exhibit various properties such as specific DNA strand-breakage activity, [1][2][3] facile dimerization, [4][5][6] unique ESR spectral behavior, [7][8][9] in vitro, induction of apoptosis 10) and mutagenesis 11,12) in vivo. It is thought that all these phenomena originate from the two natural characteristics of DHPs, i.e., their high chemical reactivity and radical generation ability. [4][5][6][7][8][9] As exemplified in Chart 1, less substituted DHPs such as 5,6-dimethyl-2,3-dihydropyrazine exhibit high chemical reactivity and readily transform to dimeric heterocyclic compounds via aldol condensation or pericyclic ene reaction (Chart 1). 5,6) In order to clarify the inherent chemical reactivity of DHPs, we studied the cycloaddition behavior of DHPs as diazadienes or imines towards ketenes. The results are discussed in detail on the basis of molecular orbital (MO) calculations on the cycloaddition pathways and the single crystal X-ray analyses of the cycloadducts. Results and DiscussionFirst, reactions of relatively stable 2,3-diphenyl DHP derivatives (1a-c) 13) with ketenes (2a-c) were performed (Chart 2).The reaction of 1a with 2a provided the 1 : 1 adduct (3aa) and two stereoisomeric 1:2 adducts (anti 4aa and syn 4aa). The yields and product ratios for the reactions with 1a-c and 2a-c are summarized in Table 1. ; 4-22-1 Ikeda, Kumamoto 860-0082, Japan. Received April 9, 2009; accepted May 7, 2009; published online May 12, 2009 The cycloaddition behavior of dihydropyrazines toward ketenes was investigated using single-crystal X-ray structures of the cycloadducts and density functional theory (DFT) calculation data. The reaction proceeds via a stepwise pathway involving an orientation complex prior to formation of the betaine intermediate. This is followed by electrocyclization to afford the 1 : 1 and 1 : 2 adducts bearing b b-lactam ring(s).

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Synthesis of Piperazines. VIII

Cited by 17 publications

References 0 publications

A Green Synthesis of Quinoxalines and 2,3-Dihydropyrazines

A Green Synthesis of Quinoxalines and 2,3-Dihydropyrazines

Steam volatile components of roasted barley

Chemical Reactivity of Dihydropyrazine Derivatives. Cycloaddition Behavior toward Ketenes

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