Pyridine benzamido

The infrared spectra of 2-, 3-, and 4-acetamido- and 2- and 3-benzamido-pyridine 1-oxides show bands characteristic of the 2-, 3-, or 4-substituted pyridine 1-oxide and of the —NHCOCH3... 

Huisgen found that 2-amino-3H-azepines are unstable under normal acylating conditions. Schotten-Baumann benzoylation, for example, brings about aromatization and, ultimately, formation of 2-(benzamido)diphenylamine, whereas p-nitrobenzoyl chloride in cold pyridine yields 2-(p-nitrophenyl)-l-phenylbenzimidazole. Benzenesulfonylation, however, proceeds normally at the exocyclic nitrogen. The mechanistic rationale for these ring contractions is outlined in Scheme 8 (b-69MI516oo). 

Consideration of rotatory powers of l,l-bis(acylamido)-l-deoxy-alditols showed79 certain correlations between optical rotation (d line of sodium) and configuration that can be summarized as follows. (a) When the acyl group is aliphatic (for example, acetyl or propionyl), the alditol will be dextrorotatory in water if the configuration of C-2 is S. (The rule does not apply to peracetylated derivatives.) (b) When the two substituents on C-l are benzamido and the configuration at C-2 is S, a solution of the alditol in pyridine will be levorotatory. Peracetylation does not alter applicability of this rule, (c) The abso-... 

Reaction of 2-aminopyridine and the ketene mercaptals (92) in the presence of sodium ethoxide gave the 2-methylthio derivatives (93).161,162 2-Amino-pyridine and 2-phenyl-4-ethoxymethylene-5-oxazole gave the condensation product 94, which in the presence of sodium ethoxide at room temperature isomerized to 3-benzamido-4-oxo-4H-pyrtdo[l,2-< /]pyrimidine.163... 

Tsuge and Noguchi469 prepared the 3-benzamido-4-oxo-4//-pyrido-[l,2-a]pyrimidine and its methyl substituted derivatives from 2-amino-pyridines and 2-phenyl-4-ethoxymethylene-5-oxazolone in boiling ethanol, without the isolation of the condensation products of type 94. The pyrido-pyrimidine was formed from 2-amino-6-methylpyridine, but in a longer reaction period and in low percentage yield. Condensation product 94 was cyclized in ethanol or polyphosphoric acid or acetic acid. 3-Benzamido-2-methyl-4-oxo-4A/-pyrido[l,2- ]pyrimidine was synthetized from 2-amino-pyridine and the appropriate oxazolone derivative. 

Amino-6-bromo-2-pyrazinecarboxamide (88) gave 3-benzamido-6-bromo-2-pyrazinecarboxamide (89) (BzCl, pyridine, 20°C, 10 h 91%), and thence 6-bromo-2-phcnyl-4(3//)-ptcridinonc (90) (0.1 M NaOH, reflux, 20 min 80%).4... 

Other variations include formamide (57JA6421), sodium dithioformate or phosphorus oxychloride-DMF (69RTC1263), a thioamide (78MI41000) and acetylacetone (77JHC813). Reduction of 2,6-dibenzamido-3-(2-butoxypyrid-5-ylazo)pyridine with iron and hydrochloric acid resulted in ring closure to 5-benzamido-2-phenylimidazo[4,5-f>]pyridine (60AC(R)125). 

Benzamido-3-cyano-4,5-dihydrothiophenes (321) cyclize at 120°C with cyclohexylamine, morpholine, piperidine, and pyrrolidine to the corresponding 4-amino-2-phenyl-5,6-dihydrothieno [2,3-d ] pyrimidines (322).181 However, when 321 and 2 equivalents of dimethylamine hydrochloride in pyridine were refluxed for 5 hr, the 4-oxothieno [2,3-d] pyrimidine 323 was formed nearly quantitatively181 (Scheme 92). Ethyl iV-(3-cyano-4,5-dihydro-2-thienyl)oxamates (324) give, with cyanomethylene compounds in the presence of triethylamine, thieno[2,3-d]pyrimidines (325).182... 

Several reactions involving jS-eliminations from 2-amino-2-deoxyhexonic acid derivatives have been reported. For example, 2-benzamido-4,6-0-benzylidene-2-deoxy-D-gluconic acid (87, R = H), on heating in pyridine... 

When the 2-benzamido-3-methylsulfonyloxy-L-iditol derivative 544 was heated with pyridine, the benzamido carbonyl attacked the back side of the carbon carrying the sulfonyloxy group to give the oxazoline 545 [63JOC442 68JCS(C)2661] (Scheme 144). 

The benzamido-group is readily eliminated to give olefins by the action of P2O5 in boiling benzene. In some cases SOClj and pyridine in ether can be employed. The elimination, which formally reverses the Ritter reaction, is illustrated by examples in Scheme 14. A transition state with carbonium ion character is indicated by the rearrangement of (436) into (438) and (439). 

Ca. 3.3 moles triethylamine added at -5 to a stirred suspension of 2-benzoyloxy-methylbenzoic acid and glycinamide hydrochloride in pyridine, then ca. 0.66 mole PClj added dropwise below 0°, and stirred 24 hrs. at 0° 2-[2-(benzoyloxy-methyl)benzamido]acetamide. Y 78%. F. e. s. B. F. Cain, J. Org. Chem. 41, 2029 (1976). 

P3Tidazine 1-oxide, 3-hydroxy-, 361 Pyridazinones, 364-368 Pyridine acetamido-, 331 acylamino-, 418-421 alkoxy-, 347 alkyl-, 426, 427 amino-, 323, 333, 404 408 benzamido-, 418... 

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