Reaction of pyridine N-oxide with acetic anhydride in anisole and in benzonitrile

Abstract

The reaction of pyridine iV-oxide and acetic anhydride in anisóle provided 22% of a mixture of 2-(o-, m-, and p-methoxyphenyl)pyridine in relative yields of 50.7:15.5:33.9, respectively. The same reaction in benzonitrile yielded 8.5% of A^-pyridylacetamide and trace quantities of A-2-pyridylbenzamide and 2-(m-and p-cyanophenyl)pyridine (relative yields of the latter, 71:29). Under the reaction conditions, A-2-pyridylbenzamide is converted to A-2-pyridylacetamide. The products are thought to arise by attack of solvent on an intermediate with an electrophilic site at the 2 position of the pyridine ring.The reaction of pyridine A-oxide (1) with acetic anhydride yields mainly 2-acetoxypyridine (2),3,3 but several side products, including 3-acetoxypyridine (3) and A-(2 '-pyridyl)-2-pyridone (4), are also formed.4 atom6,9 and any electrophilic attack that does occur on the ring leads mainly to meta-substituted products; radical attack occurs readily at the ortho and para positions of the ring.8

Self-Organization of 2-Acylaminopyridines in the Solid State and in Solution

“…Mp 73−74 °C (lit. mp 68−68.5 °C, 71 °C). 1 H NMR (CDCl 3 ) δ: 9.43 (br s, 1H, H7), 8.23−8.24 (m, 2H, H3 and H6), 7.69 (t, 3 J H,H = 8.5 Hz, 1H, H4), 7.02 (m, 1H, H5), 2.19 (s, 3H, CH 3 ); 13 C NMR: 168.98 (C8), 151.84 (C2), 147.21 (C6), 138.64 (C5), 119.53 (C4), 114.46 (C3), 24.48 (CH 3 ).…”

Rapid Fluorous Stille Coupling Reactions Conducted under Microwave Irradiation

“…Tris[2-(perfluorohexyl)ethyl]phenyltin ( 1a ), tris[2-(perfluorohexyl)ethyl](4‘-methoxyphenyl)tin ( 1b ), tris[2-(perfluorohexyl)ethyl](2‘-furyl)tin ( 1c ), and tris[2-(perfluorohexyl)ethyl](2‘-pyridyl)tin ( 1d ) were prepared as described previously. 10a,b,e Structure and purity of isolated coupling products were determined by 1 H NMR and GC−MS (>95% purity). Products 2g , 2i , 2j , 2k , 2l , 2m , and 2n , have been synthesized and fully characterized before. Compounds 2a , b , d , e , f , h are commercially available, and the structures were determined by comparison with an authentic sample ( 2d , f , h ) or by comparison of their spectroscopic data with the reported values ( 2a , b , e ). , The biaryl 2c was previously reported but not characterized …”

Conversion of N-Aromatic Amides to O-Aromatic Esters

“…Two other specific examples of the synthetic utility of this reaction are the formation of p -cyanophenyl p -methoxybenzoate (Table , example 10), a liquid crystalline compound, and 1,8-bisacetoxynaphthalene (Table , example 12), a convenient precursor to 1,8-dihydroxynaphthalenes, which are of interest as unusual ligands but are otherwise difficult to access synthetically. Heterocycles can also be used as substrates as shown for the synthesis of 2-acetoxypyridine (Table , example 14), which is essentially 2-hydroxypyridine that is protected from tautomerization to 2(1 H )-pyridone. Such molecules can be difficult to access by conventional routes.…”