Pyridine 3-methoxycarbonyl-2-chloro

The N-oxide of l-pyrrolo[2,3-b]pyridine 936 is converted by the combination tri-methylsilylisothiocyanate Me3SiNCS 937/MeOCOCl to 21% 6-isothiocyanato-l-methoxycarbonyl-pyrrolo[2,3-b]pyridine 938 and 18% 6-chloro-l-methoxycarbonyl-pyrrolo[2,3-F]pyridine 939 [51] (Scheme 7.14). To avoid formation of the chloro compound 939 a reagent combination of MesSiNCS 937 with triethylamine or DBU, which lacks any competing chloride ion, might give much higher yields of... 

Methyl-l-penten-3-one-l-ol 1 and glacial acetic acid in benzene was added to pyrrolidine to give 2-methyl-l-pen ten-1-[N-pyrrolidinyl]-3-one 2. Compound 2 when treated with oxalyl chloride and methanol was added, 3,5-dimethyl-2-methoxycarbonyl-4-pyrone 3 was produced. Treatment of compound 3 with sodium borohydride in methanol gives 3,5-dimethyl-2-hydroxymethyl-4-pyrone 4. Compound 4 was converted to 3,5-dimethyl-2-hydroxymethyl-4-pyridone 5 by heating compound 4 with aqueous ammonia in a sealed flask. Compound 5 was converted to 4-chloro-2-chloromethyl-3,5-dimethyl pyridine 6 by treatment with phosphorous oxychloride. Treatment of compound 6 with 5-methoxy-2-mer-captobenzimidazole in tetrahydrofuran gave 2-[2-(4-chloro-3,5-dimethyl pyridinyl)methylthio]-5-methoxy benzimidazole 7. When compound 7 was treated with potassium hydroxide in dimethyl sulfoxide containing methanol, 2-[2-(3,5-dimethyl-4-methoxypyridinyl)methylthio]-5-methoxy... 

Pyrazine 1-oxide and 3-amino- and 3-chloropyrazine 1-oxide with tosyl chloride in the presence of pyridine gave 2-pyridiniopyrazine chloride (14) and 2-amino- or 2-chloro-3-pyridiniopyrazine chloride, respectively and 3-methoxycarbonyl(or morpholinocarbonyl or cyano)pyrazine 1 -oxide treated similarly gave 2-methoxy-... 

Aminopyrazine was oxidized by hydrogen peroxide in acetic acid at 20° to 3-aminopyrazine 1 -oxide and at 50° for 15 hours to 2-aininopyrazine 1,4-dioxide (51%) (also obtained by similar oxidation of 3-aminopyrazine 1-oxide) (1189). m-Chloroperoxybenzoic acid was also used for the oxidation of 2-aminopyrazine to its 1-oxide (1258). The following aminopyrazine TV-oxides have been prepared by oxidation (reagent and conditions) 2-amino-3-methoxycarbonylpyrazine 1-oxide (m-chloroperoxybenzoic acid in chloroform at reflux) (880, 1222) 2-amino-5-chloro-3-methoxycarbonyl(and methylcarbamoyl)pyrazine 1-oxide (m-chloroperoxybenzoic acid in chloroform at reflux) (1222) 2-amino-5-bromo-3-methoxycarbonylpyrazine 1-oxide (wperoxyacetic acid) (906) 2-amino-3-bromo-5,6-dimethylpyrazine 1-oxide (peroxyacetic acid) (907) and 2,3-bis(pyridin-2 -yl)pyrazine 1,4-dioxide (hydrogen peroxide in sulfuric acid at room temperature) (754). 

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