2-bromo-6-methoxy benzene-, sodium

Also obtained by reaction of sodium methoxide with 2-bromo-4-(2-bromo-l-methoxypropyl)-l-methoxy-benzene in boiling methanol for 2 h [6951],... 

The diazotization of aminopyrazines has been described in earlier sections. Section V.IH records the preparation of 2-fluoropyrazine from 2-aminopyrazine in fluoroboric acid containing copper powder with sodium nitrite (882, 884) and Section V.ll the preparation of iodopyrazines from some aminopyrazines via isodiazotate salts (30) (887). These salts were assigned the isodiazotate structure, on the basis of their inability to couple with 0-naphthol in alkaline solution (887) and they were characterized by hydrolysis in cold 40% aqueous sulfuric acid to the hydroxypyrazine (887). Section V.I K describes the conversion of aminopyrazines to bromopyrazines (798, 800, 807, 890-892) for example, 2-amino-3-methoxy-carbonylpyrazine with hydrobromic acid, bromine, and sodium nitrite in water gave 2-bromo-3-methoxycarbonylpyrazine (798, 890). The diazotization of aminopyrazines to hydroxypyrazines has been described in Section VI. 1C, to alkoxy-pyrazines in Section V1.3C, and to oxopyrazines in Section V1.9A(5). 2-Amino-pyrazine with isopentyl nitrite in benzene gave 2-phenylpyrazine (45%) and some 2-isopentoxypyrazine and 2,2 -dipyrazinyl amino isomers (1211). 

It is possible to effect only partial replacement of the bromine of 2,4,6-tri-bromopyrimidine by alkoxyl when a solution of two equivalents of sodium in anhydrous ethanol is used in benzene as solvent and room temperature is not exceeded, then the product is 4-bromo-2,6-diethoxypyrimidine (89% yield).738 If the excess of ethanol is removed from a solution of sodium in ethanol and xylene by distillation and the residue is heated with 4-chloro-6-methoxy-2-pyrimidinamine for 2 hours under reflux, 4-ethoxy-6-methoxy-2-pyrimidin-amine is formed 739 but if more ethanol is present the methoxyl group is also replaced by ethoxyl and the product is 4,6-diethoxy-2-pyrimidinamine. 

Radical Arylation. The transition metal-free coupling of various aryl and heteroaryl halides via a homolytic aromatic substitution (HAS) is performed with a catalytic amount of bathophenanthroline and sodium tert-butoxide in benzene (eq 9). The reaction is compatible with functional groups such as methoxy-, cyano-, methyl-, trifluoromethyl-, phenyl-, bromo-, chloro-, iodoaryl- as well as pyridyl and thienyl with different halides (X = Cl, Br, I) with yields from 65% to 82%. The introduction of a conjugating or electron-withdrawing group increases the reactivity of the aryl haUdes. ... 

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