2- Amino-4-chloropyridine

The reaction of methyl anthranilate and 3-amino-2-chloropyridine in 1,2,4-trichlorobenzene in the presence of KOt-Bu at 50 °C gave 5,1 l-dihydro-6//-pyrido[2,3-Z)]benzodiazepin-6-one and 6-amino-ll//-pyr-ido[2,l-Z)]quinazolin-l 1-one as a by-product (99BMCL3031). 

The preparation reported here is a modification of that reported by Taylor and Crovetti.4 2-Chloronicotinonitrile has also been prepared by the dehydration of 2-chloronicotinamide 6 and by the Sandmeyer reaction on 3-amino-2-chloropyridine.6... 

After the reaction mixture of 4-amino-2-chloropyridine and EMME had been heated at 90°C for 10 hr, not only 4-pyridylaminomethylenemalonate (52), but also a malonamate derivative (53) was isolated (82CPB2399). 

The TV-protected 3-amino-2-chloropyridine derivative in 7.45. for example was found to react with styrene in the presence of a palladium acetate-triphenylphosphine catalyst system at elevated temperatures to give a near quantitative yield of a single coupling product.64 In the process sodium acetate was used as base. The formation of a single regioisomer might be attributed to the steric bulk of pyridine s substituents in position 3. 

Following a newly discovered indole synthesis, it has been shown that photochemical reaction of acetone anion with 3-amino-2-chloropyridine in liquid ammonia gives 2-methylpyrrolo[3,2-6]pyridine in 45% yield (80JOC1546). 

The condensation of 2-nitrobenzenesulfonyl chlorides with 3-amino-2-chloropyridine in the presence of pyridine at 60 °C gave the corresponding sulfonamides, which were reacted with sodium hydride and iodomethane to give the N-methylated products. Catalytic hydrogenation of the N-methylated compounds followed by acetylation, treatment with sodium hydride in DMF, and reaction with arylalkyl chlorides or methanesulfonates resulted in the formation of novel benzo[/]pyrido[]3,2-r-][l,2,5]thiadiazepines <2005JME7363>. 

The synthesis of 4-azaindole is also a photochemical synthesis and is very simple. 3-Amino-2-chloropyridine and acetaldehyde are the starting materials (Fontan et al. 1981) (Scheme 6-32). 

Intramolecular substitution of chlorine in 3-[iV-alkanesulfonyl-iV-alkyl)-amino-2-chloropyridines 455 affords pyridosultams 456 (see Section 4.05.6.3.2) <2000EJ01263, 1997TL4667>. The application of intramolecular vicarious nucleophilic substitution of hydrogen in A -oxides and quaternary salts of chloromethansulfonamides 457 (R =0, Me R = R = H) afforded isothiazolo[4,3-/ ]pyridines 458 and 459. Starting from 3-aminoquinoline 457 (R -R = -CH=CH-CH=CH-), the corresponding compounds 458 and 459 were obtained <2001T5009>. 

Selenazolopyridines 96 are obtained by using isoselenocyanates. <2003H(61)569> Heating a solution of aryl isoselenocyanates and 3-amino-2-chloropyridine in 2-propanol under reflux leads to the formation of 2-arylamino-selenazolo[5,4-7]pyridine hydrochlorides 95, the free bases 96 being liberated with aqueous NaOH (Scheme 23). 

The neurotoxic quaterpyridine natural product nemertelline was successfully synthesized by S. Rault et al. using a Suzuki cross-coupiing as the key step. The boronic acid coupling partner, required for the Suzuki reaction, was prepared by first subjecting 3-amino-2-chloropyridine to the conditions of the Sandmeyer reaction followed by a lithium-halogen exchange and trapping the lithiopyridine derivative with triisopropylborate. 

The 6,6 -diamino substituted bipyridine was generated in 52% from the dibromo bipyridine precursor in three steps (1) H2NNH2 (2) NaN02, HC1/H20 (3) NaBH4, phase transfer reagent78 The 5,5 -diamino isomer was synthesized in 60% by Ni-catalyzed homocoupling of 5-amino-2-chloropyridine.79... 

A method for the synthesis of the benzodiazepine derivative (264) by the condensation of anhydride 1 with 3-amino-2-chloropyridine (264) and treatment of the obtained amino amide (265) at 200-210°C was filed in the patent [176],... 

Boron Reagents. The Suzuki coupling with methylboronic acid and 2-chloro-3-nitropyridine gives the 2-methyl product 249 (Scheme 91) in high yield. 3-Amino-2-chloropyridine reacts less readily and 2-chloropyridine failed to react. 

Exactly the same method was successfully employed in the synthesis of 2,2 -bipyridines bearing a free amino group. Thus 4,4 -diamino-2,2 -bipyridine was prepared from 5-amino-2-chloropyridine in 60% yield, respectively [38]. Nickel-catalysed synthesis of biaryls and related vinyl halides were successfully used in a great number of examples [39,40], including the strained aromatic ether-sulfone oligomers [41]. For instance, compound 84 was cyclized to a very strained cyclic... 

Amino-2-methoxypyridine is acetylated to give the acetyl derivative that, when treated with perbenzoic acid in chloroform, gives 4-amino-2-methoxy-pyridine-1-oxide. Similarly, 4-amino-3-chloropyridine-l-oxide is obtained from 4-amino-2-chloropyridine. 

Amino-2-chloropyridine (X-107, X = NHj), obtained by reduction of the 5-nitro precursor (X-107, X = N02), was converted by a Sandmeyer reaction to the 5-cyano-compound (X-107, X = CN). Saponification afforded 5-carboxylic acid (X-107, X = CO2H), which, on treatment with potassium hydrogen sulfide, yielded 2-mercaptopyridine-5-carboxylic acid (X-108, Y = SH). The latter was oxidized with alkaline permanganate to the 2-sulfonic acid (X-108, Y = S03H). 

A second Sandmeyer reaction on S-amino-2-chloropyridine (X-107, X = NH2) and copper-catalyzed coupling with SO2-saturated acetic acid gave the 2-chloropytidine-5-sulfonic acid (X-109, X = Cl). This substance was converted... 

Starting with 3-amino-2-chloropyridine (X), the following sequence of reactions is carried out ... 

Whilst 5-amino-2-chloropyridine reacted readily with nitrosobenzene in acetic acid, giving 2-chloro-5-phenylazopyridine387d 2- and 4-aminopyridine did not react with j -nitrosodimethylaniline under these conditions389. The failure has been attributed to protonation of both the aminopyridines and the nitroso compound and indeed 2-, 3- and 4-aminopyridines4 7 and their... 

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