CXCII.—The resolution of benzoyloscine

Tutin, Frank

doi:10.1039/ct9109701793

Cited by 6 publications

(6 citation statements)

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“…The use of ammonia may lead to other complications, such as resin formation. This was found true in the attempted conversions of p-methoxy-co-chloroacetophenone (224) and -chloromethyl ethyl ketone (128) to the corresponding pyrazines. In such cases the amination may successfully be accomplished by the Gabriel phthalimide method.…”

Section: Rc=(noh)cor'mentioning

confidence: 83%

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The Pyrazines.

Krems¹,

Spoerri²

1947

Chem. Rev.

149

173

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Section: Rc=(noh)cor'mentioning

confidence: 83%

“…Hydroxypyrazine and acetic anhydride Acetoxypyrazine (76,77) Di -o-liy droxy phenyl pyrazine and benzoyl chloride Di-o-benzoyloxy-2,5-diphenylpyrazine (224) , o ', p, p'-Tetrahydroxy-2,5-diphenylpyrazine o,o', p,p'-Tetrabenzoyloxy-2,5-diphenylpyrazine (224) benzoyl chloride. These reactions are listed in table 25.…”

Section: S-chmentioning

confidence: 99%

The Pyrazines.

Krems¹,

Spoerri²

1947

Chem. Rev.

149

173

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“…However, the reaction was found to yield the unexpected products 2,6-diarylpyrazines in good yield. This novel preparation of 2,6-diarylpyrazines attracted our attention because of the very low yields (10-30%) of literature preparations of 2,6-diarylpyrazines [5][6][7] Correspondence to: Guofeng Jia ᭧ 1998 John Wiley & Sons, Inc.…”

Section: Introductionmentioning

confidence: 99%

A facile preparation of 2,6-diarylpyrazines

1998

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2,6‐Diarylpyrazines were prepared in good yields by a novel method of condensing methoxycarbonylhydrazine with N,N‐bis(arylcarbonylmethyl)‐p‐toluenesulfonamides, unsymmetrical derivatives of which were synthesized by a new (or different) procedure. The structures of these 2,6‐diarylpyrazines were established by spectral data and X‐ray diffraction analysis. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:341–345, 1998

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“…Use of pyrazine compounds for flavor ingredients has, therefore, become increasingly popular recently. Various methods of pyrazine synthesis have also been reported (Tutin, 1910;Cormforth, 1958;Flament and Stoll, 1967; Bramwell et al, 1971). Ishiguruo and Matsumura (1958) obtained alkylpyrazines from corresponding 2,3dihydropyrazines by heating in an ethanol-KOH solution under aerobic conditions.…”

mentioning

confidence: 99%

Preparation of 5-substituted 2,3-dimethylpyrazines from the reaction of 2,3-dimethyl-5,6-dihydropyrazine and aldehydes or ketones

Masuda¹,

Tanaka²,

Akiyama³

et al. 1980

J. Agric. Food Chem.

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The dehydrogenation reaction of 2,3-dimethyl-5,6-dihydropyrazine produced 2,3-dimethyl-l,2,5,6tetrahydropyrazine (25.4%) and 5-ethyl-2,3-dimethylpyrazine (2%) in addition to 2,3-dimethylpyrazine (26.7%) in a sodium ethoxide/ethanol solution. It was suspected that the carbanion of 2,3-dimethyl-5,6-dihydropyrazine was formed with the base and then reacted with acetaldehyde, which is present in ethanol in small quantities, to yield 5-substituted pyrazine. Six aldehydes and three ketones were reacted with 2,3-dimethyl-5,6-dihydropyrazine under basic conditions and the corresponding 5-substituted 2,3-dimethylpyrazine were obtained in high yields.Pyrazines have received much attention in the last decade as the flavor chemicals which possess roasted or smoky odor (Watanabe and Sato, 1971;Buttery et al., 1971). Use of pyrazine compounds for flavor ingredients has, therefore, become increasingly popular recently. Various methods of pyrazine synthesis have also been reported (Tutin, 1910;Cormforth, 1958;Flament and Stoll, 1967; Bramwell et al., 1971). Ishiguruo and Matsumura (1958) obtained alkylpyrazines from corresponding 2,3dihydropyrazines by heating in an ethanol-KOH solution under aerobic conditions. The yield of expected pyrazines by this method is, however, usually low. We found that dehydrogenation of dihydropyrazines also occurred in an ethanol-KOH solution or metal alkoxide solution under nitrogen stream. When 2,3-dimethyl-5,6-dihydropyrazine and 5-ethyl-2,3-dimethylpyrazine, which was expected to be formed from the reaction of carbanion and acetaldehyde (Shibamoto et al., 1979), were obtained as byproducts in addition to 2,3-dimethylpyrazine.Following this procedure, the various 5-substituted 2.3-dimethylpyrazines were obtained in high yields from the reaction of 2,3-dimethyl-5,6-dihydropyrazines with aldehydes and ketones in a metal alkoxide solution. EXPERIMENTAL SECTION Materials. Diacetyl (Naarden Inc.) and ethylenediamine (Nakari Chemicals Ltd.) were used after distillation.2.3-Dihydropyrazines were synthesized from corresponding dicarbonyls and diamines (Ishiguro and Matsumura, 1958).Methanol and ethanol were purified with magnesium under a nitrogen stream. Propanol, 2-propanol, and 2methyl-2-propanol were purified with calcium hydride under a nitrogen stream. Aldehydes and ketones were obtained from reliable commercial sources and used after distillation. IR, NMR, and MS data were obtained on JASCO IR-S, JNM-PMX 60, and Hitachi Model RMU-6M, respectively.Isolation of 2,3-Dimethylpyrazine (II), 2,3-Dimethyl-l,2,5,6-tetrahydropyrazine (III), and 5-Ethyl-2,3-dimethylpyrazine (IV) from the Reaction of 2,3-Dimethyl-5,6-dihydropyrazine (I) in a Sodium Ethoxide/Methanol Solution. Compound I (42 g) was dissolved into a mixture of methanol (200 mL) and sodium ethoxide (18 g of sodium metal in 360 mL of ethanol). The

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CXCII.—The resolution of benzoyloscine

Cited by 6 publications

References 0 publications

The Pyrazines.

The Pyrazines.

A facile preparation of 2,6-diarylpyrazines

Preparation of 5-substituted 2,3-dimethylpyrazines from the reaction of 2,3-dimethyl-5,6-dihydropyrazine and aldehydes or ketones

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