2-Pyridyl benzoate

Electrophilic C-acylation of pyridine is practically unknown. The exception is the surprising report that pyridine reacts with V-methylformanilide and phosphoryl chloride to give a small yield of pyridine-2-aldehydei30. Xhe reported orientation makes the report suspect. The Friedel-Crafts method fails, presumably because the acylium cation is not active enough to attack the pyridine nucleus deactivated by coordination with aluminium chloride (cf the case of chlorination below). Even the much more reactive 2 hydroxy-pyridine cannot be C-acylated, though 2-pyridyl benzoate gives a trace of 5-benzoyl-2-hydroxypyridine in the Fries rearrangementi i. 

Figure 13 Coordination environment (a) and diamondoid structure (b) of [ Cd[4-(4-pyridyl) benzoate]2 H20] (reproduced by permission of the American Chemical Society from Chem. Mater.,...

A similar effect was seen in a comparison of the rates of transesteriflcation, under similar conditions, of 2-pyridyl (16) and 4-pyridyl benzoate (17). ° There the formation of a six-membered cyclic transition state (18) for the 2-isomer explained its faster rate. 

The esters of hydroxypyridines with carboxylic acids are all easily hydrolysed, but the 3-pyridyl esters are more stable than the other isomers. The esters of 4-hydroxypyridine must be prepared under anhydrous conditions a The catalytic hydrogenolysis of pyridyl benzoates and />-toluenesulphonates has been described (p. 264). 

Figure 6-11. 1 -H-Benzotriazole, 2,5-bis(N-pyridyl)-1,3,4-oxadiazole, cyclohexylammonium benzoate, benzylsulfonylacetic acid, 2,4-diamino-6-mercapto pyrimidine, hydroxamic acid, 3-phenyl-2-propyn-1-ol, dicyclopentadiene dicarboxylic acid.

Tris(oxazoline) complexes have also been investigated as ligands in the allylic oxidation reaction. Katsuki and co-workers (116) observed that Cu(OTf)2 com-plexed to the tris(oxazoline) 160 is a more selective catalyst than one derived from CuOTf, Eq. 99, in direct contrast to results observed with bis(oxazohnes) or pyridyl bis(oxazohnes) as ligands (cf. Section III.A.3). When the reaction is conducted at -20°C, the cyclopentenyl benzoate is delivered in 88% ee albeit in only 11% yield after 111 h. Larger cycloalkenes are less selective (cyclohexene 56% ee, cyclohep-tene 14% ee, cyclooctene 54% ee). 

Cyclization of 2-[(3-acetamido-2-pyridyl)amino]benzoic acid (202) in 0.5 N sulfuric acid gave 6-amino-ll//-pyrido[2,l-h]quinazolin-ll-one (203) (84MI3). 2-[(6-Methyl-, 5-nitro-, and 3-nitro-2-pyridyl)amino]benzoic acids were cyclized into 9-methyl, 8-nitro, and 6-nitro-l 1 //-pyrido[2,l -ujquina-zolin-ll-ones, respectively, by the action of 80% sulfuric acid. Ethyl 2-(2-pyridylamino)benzoate, prepared in the reaction of 2-chloropyridine and ethyl anthranilate in boiling toluene for 10 h, afforded ll//-pyrido[2,l-b]-quinazolin-ll-one (27) on heating at 200-210°C for 0.5 h (92MI2). 

Allylic Oxidation. The Kharasch-Sosnovsky reaction involves oxidation of the allylic position while the olefin remains intact. In the presence of catalytic copper (II) salts, treatment of olefins with peresters affords acylated allylic alcohols. When (S)-(—)-4-(2-methylpropyl)-2-(2-pyridyl)-2-oxazoline was involved, (R)-cyclohexenyl benzoate was isolated in 57% yield and 28% ee (eq 6). ... 

C12H15N02 acrylic acid 2-(5 -ethyl-2-pyridyl)ethyl est 122-93-0 435.90 37.761 2 24226 Cl 2H1602 methyl 4-tert-butyl benzoate 26537-19-9 516.50 45.472 2... 

Fig. 4.20 a Variously substituted benzoate salts of l-phenylalanine-3-pyridyl amide studied for gelation b ID HBN displaying PAM synthon W with additional hydrogen bonding in the crystal structures of the gelators G44 (X = 4-Cl, 4-Br, 4-NO2, 4-Me) c i Au NPs adhered to the rod and spherical shaped gel network, ii. Hi enlarged view of the Au NPs adhered to spherical and rod gel network, respectively, iv size distribution of the Au NPs, v surface plasmon peak of the Au NPs d selected area electron diffraction of the Au NPs, vi aggregated reduced Au particles produced in the aqueous solution of 044 (X = 4-Me). Reproduced from Ref. [82] by permission of John Wiley Sons Ltd... 

The acylation of 3-dimethylamino-l-(2-pyridyl)propane (IX-289) and 3-dimethylamino-l-phenyl-1-(2-pyridyl)propane (IX-290) with various esters using phenyllithium or phenylsodium as the base to produce the carbanion yields the ketones IX-291. For example, when the ester is ethyl benzoate, the ketone IX-291, (Rj = H, Rj = CgHj) is obtained. ... 

Acetyl or benzoyl chloride and 2-picoline-1-oxide in nonaqueous solvents give the acetate or benzoate of 2-pyridinemethanol and a small amount of 2-pyridylmethyl chloride " Pyridine-1 -oxide and tosyl chloride in benzene give 2,3-dipyridyl ether, AT-(2 -pyridyl)-2-pyridone, A -<2 -pyridyl)-5-chloro-2-pyri-done, A (2 -pyridyl)-3-chloro-2-pyridone, and 3-tosyloxypyridine. Tracer studies have suggested that the 3-tosyloxypyridine is formed via an intimate ion pair (xn-443). (For alternate suggestion, see Ch. I). 

Pyridyl methacrylate has been prepared from the sodium salt of 2-pyridone and methacryl chloride and has been polymerized by radicals but not by anions. 2-Pyridone and phosgene (1 4) in dry tetrahydrofuran or benzene with or without pyridine form di-(a-pyridyl)carbonate, which is a useful reagent for the formation of the benzoate and the monophenyl phosphate of 2-pyridone. ... 

As another ligand the 5,10,15,20-tetracarboxytetraphenylporphyrin 21 (R = OOH) was employed [350]. The Zn-complex of this porphyrin was treated with 4,4 -bipyridine in a mixture of methanol and ethyl benzoate to give crystals of 94. Figure 19 shows interlinked arrays of the porphyrin and bipyridyl. The strueture represents an open three-dimensional network in which the individual metallo porphyrin units are eross-linked both axially as well as equatorially by ion-impairing interactions. Partially pyridyl-substituted porphyrins are reacted with PdCl2 to definite oligomers [351]. 

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