2- Methyl-6-vinyl-pyrazines

Dimethylpyrazine (48) and the cationic bis(cyclopentadienyl) zirconium complex (49) gave an isolable intermediate formulated as the complex (50) and thence 2,5-dimethyl-3-(pent-l-enyl) pyrazine (51) [one pot procedure complex (49), CH2C12, 23°C, 15 min then HC=CPr J, 23°C, 2.5 h 88%] 868 several analogues, like 2,5-dimethyl-3,6-bis[l-methyl-2-(trimethylsilyl)-vinyl] pyrazine (51a) (61%), were made similarly.868... 

Methylpyrazine (300) gave 2-[2-(l-methylpyrrol-2-yl)vinyl]pyrazine (299) [NaH, Me2NCHO, 60°C, N2, 1 h then l-methyl-2-pyrrolecarbaldehyde J, 50°C, 5 h 40% compare conditions with those required for alkylidenation of the more activated methyl group in substrate (297)].1485... 

A patent (726) has described the preparation of 2methyl-pyrazine by reaction with ammonia and air at 350° over a catalyst containing vanadium pentoxide and potassium sulfate a series of cyanomethylpyrazines has been prepared from the corresponding methylpyrazines by reaction with sodium amide in liquid ammonia followed by Af-methyl-A -phenylcyanamide in dioxane (644). 2-Hydroxyiminomethylpyrazine has been prepared from 2-methylpyrazine, sodium amide, and liquid ammonia with butyl nitrite (727, 728), and 2-hydroxy-iminomethyl-3,6-dimethyI-5-pentylpyrazine similarly from 2,3,5-trimethyl-6-pentylpyrazine (648). Nitrones (28) have been prepared from 23-and 2,5-dimethyl-and tetramethylpyrazine through the substituted methylpyridinium (perchlorates) (27) by reaction with p-nitroso-A, fV-dimethylaniline (729). Dehydrogenation of ethylpyrazine at 600° over a calcium cobaltous phosphate catalyst gives 2-vinyl-pyrazine (658). 

CIC the earthy odour of fresh potatoes is represented by 2-isopropyl-3-methoxy pyrazine. This earthy note is supported by the mushroom character of l-octen-3-ol. The key component of boiled potatoes is 3-(methylthio)-propanal, balanced with dimethyl sulphide. The high reaction temperatures in baked and fried potatoes start the Maillard reaction to form mainly heterocyclic components 2-ethyl-3,5-dimethyl pyrazine, 2-ethyl-6-vinyl pyrazine, 5-methyl-6,7-dihydro-(5H)cyclopenta-pyrazine, 2-acetyl-l,4,5,6-tetrahydro-pyridine are responsible for the roasted, nutty cracker-like flavour. The heat-induced degradation of the potato lipids and the frying oil imparts a fatty, tallowy character to the french fried potatoes. (E,E)-2,4-Decadienal, 2-octenal, octanoic acid and decanoic acid are main contributors to this fatty note. 

Pyrazine, tetrahydro-, 3, 177, 178 Pyrazine, 1,2,3,4-tetrahydro-synthesis, 3, 177 Pyrazine, 2,3,5-tri-t-butyl-synthesis, 3, 185 Pyrazine, 2,3,5-trichloro-nucleophilic substitution, 3, 176 Pyrazine, 2-vinyl-polymers, 1, 290-291 Pyrazine-3-carboxylic acid, 2-amino-methyl ester... 

The vinyl triflate of Komfeld s ketone has been subjected to Heck reactions with methyl acrylate, methyl methacrylate, and methyl 3-(Af-rerf-butoxycarbonyl-lV-methyl)amino-2-methylenepropionate leading to a formal synthesis of lysergic acid [259]. A similar Heck reaction between l-(phenylsulfonyl)indol-5-yl triflate and dehydroalanine methyl ester was described by this research group [260]. Chloropyrazines undergo Heck couplings with both indole and 1-tosylindole, and these reactions are discussed in the pyrazine Chapter [261], Rajeswaran and Srinivasan described an interesting arylation of bromomethyl indole 229 with arenes [262]. Subsequent desulfurization and hydrolysis furnishes 2-arylmethylindoles 230. Bis-indole 231 was also prepared in this study. 

Even reactions which are thermodynamically unfavoured, e.g. with Kaq as low as 5 x 10-6, may be electrocatalytically mediated. For example, rotating platinum electrodes covered with polymerized [Ru(4-vinyl-4 -methyl-2,2 -bipyridyl)3]2+wiil electrocatalytically mediate the oxidation96 of such species as [Ru(bipy)3]2+, [Ru(bipy)2(4,4 -bipy)2]2+, [Ru(bipy)2(py)(MeCN)]2+, [Ru(bipy)2-(MeCN)J2+ and [Ru(bipy)2(pyrazine)2]2+. 

Pyrazine, 2-ethenyl-6-methyl-, 2-methyl-6-vinylpyrazine, 2-vinyl-6-methylpyrazine [13925-09-2]... 

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