5-Amino-3-hydroxy-2-methylpyridine

In comparison with mercapto-, hydroxy-, and amino-pyridines, methylpyridines should show an even greater tendency to exist in the methyl form [instead of as pyridmethines (297)] than do the amino compounds to exist as such. If the methyl carbon atom carries an electron-withdrawing group, it might be expected that structures of type 297 would be stabilized. Fused benzo groups should also tend to stabilize the methine form, and tautomerism involving 298 has, in-... 

Mendel44 found that reaction of 2-aminopyridine-3-carboxylic acid with ethyl acetoacetate or ethyl benzoylacetate gave rise to a decarboxylated product (36 R1 = Me, Ph R = R2 = H), whereas with ethyl 4,4,4-tri-fluoroacetoacetate, the product was ethyl 2-aminopyridine-3-carboxylate. Yale51 obtained 3-benzoyl-2-hydroxy-4-oxo-4ff-pyrido[ 1,2-a] pyrimidine in 4- 5%, yield from 2-amino-3-methylpyridine and ethyl benzoylacetate in diethylbenzene. 

Other Ditungsten(II) Complexes. The 2-oxopyridine type ligand I, and related monoanionic ligand bridges such as 2-amino-6-methylpyridine and 2,4-dimethyl-6-hydroxy-pyrimidine have played an important role in the development of the chemistry of quad-... 

This procedure is a modification of that reported by Adger and co-workers.2 Both 2-hydroxy-4-methylpyridine and 2-hydroxy-6-methylpyridine can be obtained from Aldrich Chemical Company, Inc. However, it is more economical to prepare them In large quantities using this procedure from 2-amino-4-methylpyridine and 2-amino-6-methylpyridine, respectively. 

Hydroxy-4-methylpyridine 2(1 H)-Pyridinone, 4-methyl- (9) (13466-41-6) 2-Hydroxy-6-methylpyridine 2(1 H)-Pyridinone, 6-methyl- (9) (3279-76-3) 2-Amino-4-methylpyridine Aldrich Name 2-Amino-4-picoline Highly Toxic 4-Picoline, 2-amino- (8) 2-Pyridinamine, 4-methyl- (9) (695-34-1) 2-Amino-6-methylpyridine Aldrich Name 2-Amino-6-picoline Highly Toxic 2-Picoline, 6-amino- (8) 2-Pyridinamine, 6-methyl- (9) (1824-81-3) N-Benzylbenzamide Benzamide, N-benzyl- (8) Benzamide, N-(phenylmethyl)- (9) (1485-70-7)... 

Hmhp = 2-hydroxy-6-methylpyridine. Hmap = 2-amino-6-methylpyridine. dmp = 2,6-dimethoxy-... 

Hmhp = 2-hydroxy-6-methylpyridine. b Hmap = 2-amino-6-methylpyridme. c dmp = 2,6-dimethoxy-phenyl. d Hambt = 2-amino-4-methylbenzothiazole. ° dppe = l,2-bis(diphenylphosphino)cthane. pic = 4-methylpyridine. 

Pyridoxol 210 (pyridoxine, 3-hydroxy-4,5-bis(hydroxymethyl)-2-methylpyridine, vitamin B6) was formerly known as adermine (Kuhn 1938) because vitamin B5 deficiency causes skin diseases in animals. Pyridoxal (211, R = CHO) and pyridoxamine (211, R = CH2NH2) also belong to the vitamin B group. Pyridoxal phosphate 212 is a coenzyme for many of the enzymes involved in the metabolism of amino acids. Nicotinamide adenine dinucleotide 213 (NAD , reduced form NADH) is a component of oxidoreductases (for its action see p 293, synthesis see p 131). 

Hydroxy-6-methylpyridine-3 Carboxylic acid (DC-102), a metabolite of piyridoxamvne in Pseudomonas MA, has now been synthesized from S-amino-2-chlorO 6-methyIpyridine-3-carboxylic acid (DC-101) by hydrogenation... 

With educts containing an axially oriented LG at C-3, in addition to an intramolecular Sn2 reaction with an axially oriented hydroxy or acetamido group in a vicinal position (IS, Table 3, entries 1 [26] and 2 [30]), elimination and/or hydride shift (E or M/E, entries 3 [30],4 [31] and 6 [32]), as well as substitution with retention of configuration (AS, entries 7 and 8 [27b]) have been observed. For the transformation outhned in entry 4, 2,6-di-ferf-butyl-4-methylpyridine was used as acid scavenger, since pyridine per se in a similar reaction had caused Sn2 displacement (entry 5 [33]). Of special interest are the results from the deamination of methyl 3-amino-3-deoxy-/5-D-allopyranoside (entry 6), where the main reaction consists of direct Sn2 displacement with formation of methyl... 

Quaternary amino substituents on the pyridine ring can also be replaced. The important example is that of 4-pyridylpyridinium chloride hydrochloride which is converted into 4-hydroxypyridine when heated with water 33, 435, 437, 442a 4-Hydroxy-3-methylpyridine is prepared in the same... 

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