6-Methoxy-3-nitropyridine

Ethoxalylmethyl-6-methoxy-3-nitropyridine (9) underwent reductive cycliza-tion to 3-hydroxy-6-methoxy-3,4-di hydro-1,5-naphthyridin-2(l//)-one (10) (Pt02, H2, 3 atm, EtOH, 20°C, 2 h 69%) that was easily aromatized to give 6-methoxy-1,5-naphthyridine-2,3( 1 //, 5//)-dione (11) [TsCl, pyridine, 150°C ( ), 4h 83%] 234... 

The reaction of 4-methoxy-3-nitropyridines 129 with guanidine under similar conditions results in 3-aminopyrido[3,4-e]-l,2,4-triazine 1-oxides 130 (76MI). 

Having established that the end game of the proposed synthesis of cylindrospermopsin (1) from bromoketone 4 was viable, we turned our attention to the preparation of acetylene 5 from 4-methoxy-3-methylpyridine (7). 4-Methoxy-3-methylpyridine (7) was prepared by modifications of the literature procedure.17,18 3-Methyl-4-nitropyridine A-oxide (27),19 was treated with K2CO3 in methanol at 70 °C to displace the nitro group to... 

Aminopyridine 2-Aminopyridine 2-Methoxy-5-nitropyridine 2-Hydroxy-5-nitropyridine... 

Scheme 43 HJR of 2,6-dimethoxypyridine (158) and 2-methoxy-5-nitropyridine (160) with haloalkanes [103]...

Methoxy-5-nitropyridine (59) with l-phenyl-3-phenylsulfonylpropane (60) gave 2-methyl-6-phenyl-8-phenylsulfonyl-l,5-naphthyridine (61) (reactants,... 

All these amination reactions show exclusive SNH substitution. There is hardly any indication for the formation of 3-nitropyridines, in which the chloro or methoxy group was replaced by an amino group, even when these leaving groups are present at the reactive a-position of the pyridine ring. It seems to be a characteristic feature of the oxidative amination... 

Methoxy-5-nitropyridine (126) reacts readily with Af,/V-dimethyl-ethylenediamine in boiling water to give 89% of 127 (85EUP136730). Analogously, 4-ethoxy-3-nitropyridine-hydrochloride (128), is heated at reflux for 8.5 hr with an aqueous solution of ammonium acetate to afford 87% of 3-nitro-4-aminopyridine (129) (85EUP149537). 

C7H7N04 2-methoxy-5-nitrophenoi 636-93-1 25.00 1.3375 2 10828 C7H8N203 3-ethoxy-2-nitropyridine 74037-50-6 20.00 1 2089 2... 

In an abnormal von Richter rearrangement, 2,6-dimethyl-3-nitropyridine reacts with potassium cyanide in methanol to give a mixture of 3-methoxy-6-methylpyridine-2-carbonitrile 1-oxide and 6,8-dimcthylpyrido[3,4-ring carbon in the 2-position of the pyrido[3,4-e ]pyrimidine originates from the 2-methyl group of the educt.420... 

Methoxy-4-methyl-5-nitropyridine is an intermediate used in a synthesis of porphobilinogen (section 13.18.3.1). 

The synthesis of porphobilinogen from 2-methoxy-4-methyl-5-nitropyridine (section 5.15.2.3) is an example of a Reissert-type synthesis (section 17.16.1.2) affording in this case a 6-azaindole as an intermediate. 

Scheme 48. Improved synthesis of 2-chloro-3-methoxy-4-nitropyridine N-oxide 310).

Preparation of the 2-chloro-3-methoxy-4-nitropyridine A -oxide intermediate in the synthesis was considerably improved by the methylation of commercially available 2-chloro-3-pyridinol using dimethylsulfate and tet-rabutylammonium bromide as the catalyst under phase-transfer conditions (370), instead of diazomethane (Scheme 48). In the synthesis of orellanines elaborated by Tiecco et al. (299,301,309), shown in Scheme 49, the commercially available 3-hydroxypyridine was the starting material. The structures of the synthetic compounds were proved to be identical to those... 

A similar VNS cyanomethylation of 3-nitropyridine and subsequent hydrogena-ti(Mi of the so-formed ort/io-nitropyridyl-substituted acetonitriles provided 4- and 6-azaindoles. The VNS of hydrogen in 2-methoxy-5-nitropyridine with the carb-anion of aiyloxyacetonitrile leads to pyridylacetonitrile. Alkylation of the latter with hromoacetOTiitrile followed by a two-step reduction efficiently results in the formation of 5-azamelatonin (Scheme 69) [187]. Condensation of pyridyl-substituted acetonitriles with aromatic aldehydes followed by catalytic reduction gave 3-benzyl-4-azaindoles [187],... 

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