The Action of Organolithium Compounds on 2,5-Dimethylpyrazine. II¹

Bioinspired design of redox-active ligands for multielectron catalysis: effects of positioning pyrazine reservoirs on cobalt for electro- and photocatalytic generation of hydrogen from water

“…Notably, lithiations were performed with the sterically-hindered base lithium diisopropylamide when deprotonating pyrazine-based reagents, as the more nucleophilic reagent n-butyl lithium resulted in alkylation of This journal is © The Royal Society of Chemistry 2015 the pyrazine ring. 71 Moreover, successful coupling of ligand fragments is governed by appropriate matching of nucleophilic and electrophilic partners, and thoughtful attention to each stepwise synthetic sequence is required. For example, several attempts were made to react 3a with PY3MeF to form 3, including an extended reux in 1,4-dioxane, but no synthetically useful conversion was observed.…”

Recherches sur les arǒmes 14ecommunication [1] Sur 1′arǒme de café, II Pyrazines et pyridines

“…Au cours de l'analyse de l'arbme de cafC, qui a fait l'objet du mCmoire prCcCdent [l], nous avons identifit5 bon nombre de composants basiques, et parmi ceux-ci une sCrie de pyrazines. Certaines ont CtC isolCes dans les extraits GF8 et GF9, mais la plupart des pyrazines identifikes proviennent de l'analyse de l'extrait GFlO et se retrouvent plus particuli6rement dans les fractions [II (12)(13)(14)(15)(16)(17)(18)(19) + III(7-10)] (voir [l], Fig. 1. Courbe CG sche'matique de l'extrait I SUY phase n o n polaire (huile de silicone) schCma IV, p. 657) et C3 (voir [l], schCma V et VI, pp.…”

“…SM. : 122 (97,0), 121 (loo), 107 (5,0), 94 (19,7), 81 (15,7), 67 (30,4), 52 (8,4), 42 (15,7), 39 (16,3), 26 (12,9).…”

The preparation and some reactions of 3,6‐dimethyl‐2‐pyraziny llithium

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The widespread use of the halogen-metal interconversion reaction in the preparation of organolithium compounds, in which the metal is directly attached to a variety of heterocyclic ring systems i s well documented (2). A survey of the literature reveals however, that no organometallic derivative of pyrazine, in which the metal i s directly attached to the pyrazine nucleus has been prepared, although a number of attempts utilizing chloro and bromopyrazines have been reported (3,4,5). It has now been found that a pyrazinyllithium derivative can be readily obtained by halogenmetal interconversion using a more reactive iodopyrazine derivative (6).Addition of an ether solution of n-butyllithium to a solution of 2-iodo-3,6-dimethylpyrazine (I) in ether resulted in the formation of a reddish mixture.Carbonation of this mixture allowed the isolation of a solid which proved to be 3,6-dimethyl-a-pyrazinoic acid monohydrate (II), a compound previously prepared by Sbehr (7) by the selective oxidation of 2-ethyl-3,6-dimethylpyrazine (III).A comparison sample of the acid was prepared by the hydrolysis of 2-cyano-3,6-dimethylpyrazine (N), a new compound readily synthesized by treating 2-iodo-3,6-dimethylpyrazine (I) with cuprous cyanide in refluxing 3-picoline (8).

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“…The Preparation and Some Reactions of 3,6-Dimethyl-2 -pyrazinyllit hium ( l a ) Albert Hinchberg (lb), Alan Peterkofiky, and Paul E. Spoerri (lc) The widespread use of the halogen-metal interconversion reaction in the preparation of organolithium compounds, in which the metal is directly attached to a variety of heterocyclic ring systems i s well documented (2). A survey of the literature reveals however, that no organometallic derivative of pyrazine, in which the metal i s directly attached to the pyrazine nucleus has been prepared, although a number of attempts utilizing chloro and bromopyrazines have been reported (3,4,5). It has now been found that a pyrazinyllithium derivative can be readily obtained by halogenmetal interconversion using a more reactive iodopyrazine derivative (6).…”