Pyridines 2-amino-, 3-alkylation

Reductive alkylation by alcohol solvents may occur as an unwanted side reaction 22,39), and it is to avoid this reaction that Freifelder (20) recom mends ruthenium instead of nickel in pyridine hydrogenation. Alkylation by alcohols may occur with surprising ease 67). Reduction of 18 in ethanol over 10% palladium-on carbon to an amino acid, followed bycyclization with /V,/V-dicyclohexylcarbodiimide gave a mixture of 19 and 20 wiih the major product being the /V-ethyl derivative 49,50). By carrying out the reduction in acetic acid, 20 was obtained as the sole cyclized product 40). 

Corrections are applied to 15 structural types (e.g., alcohols/acids selected phenols, nitros, amines, alkyl pyridines, amino acids, PAHs, multi-nitrogen types, etc.). Application and magnitude depend on available MP. 

Unlike simple alkyl halides, ethyl chloroformate appears to react with primary and secondary amino groups in any position to give directly the corresponding urethane, e.g. (258) (64JMC364). Such alkylations proceed in pyridine, aqueous alkali or even warm benzene (62JOC982). 

In 1949, by comparison of the ultraviolet spectra of 2- and 4-amino-pyridine with those of the alkylated forms of the alternative tautomers, Anderson and Seeger showed that the parent compounds existed predominantly in the amino form and reported that the tautomeric composition did not vary greatly with the temperature. By using the pK method, in 1952 Angyal and AngyaP showed that... 

Alkylation of 3-amino-4-(pyrid-3-yl)furazan occurred at the pyridine ring (Scheme 111) (90EUP384288) (see also Scheme 187). 

A ketoxime tosylate 1 can be converted into an a-amino ketone 2 via the Neber rearrangement by treatment with a base—e.g. using an ethoxide or pyridine. Substituent R is usually aryl, but may as well be alkyl or H substituent R can be alkyl or aryl, but not H. 

Methyl or ethyl chloroformate (70 mmol) was added dropwise to a stirred solution of a hydrazone derivative (60 mmol) of 2-amino-5-chlorobcnzophenone in a mixture of CIICI, (200 mL) and pyridine (15 mL) at 10 C. The mixture was left overnight and treated with a further amount of the alkyl chloroformate (40 mmol) and stirred at 20 C for 2 h. If /V-aryl-substituted hydrazones were used, the mixture was refluxed for 3-6 h. The mixture was poured into ice-water and the organic layer was washed successively with H2Oand 10% aq NaH0O3, dried (MgSO ) and evaporated in vacuo to yield 7 or 8 or a mixture of the two. 

Pyran, tetrahydro-, 3 chloro 2 methyl [2H Pyran, tetrahydro, 3 chloro-2-mcthyl ], cis, trans mixture, 55, 64 2-PYRAZOLIN-5-ONES, 3-alkyl-, 55, 73 2-Pyrazolin 5-one, 3-(l-propyl)-, 55, 73 Pyridine, 2-amino-, p-bromination of, 55, 23... 

When an a-amino acid is treated with an anhydride in the presence of pyridine, the carboxyl group is replaced by an acyl group and the NH2 becomes acylated. This is called the Dakin-West reaction The mechanism involves formation of an oxazolone. The reaction sometimes takes place on carboxylic acids even when an amino group is not present. A number of N-substituted amino acids, RCH-(NHR )COOH, give the corresponding N-alkylated products. 

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