Methyl 2-hydroxy-6-methylisonicotinate

This compound is typically obtained as a white to off-white crystalline powder. Its molecular formula is C8H9NO3, corresponding to a molecular weight of 167.16. The melting point generally falls within the range of 158–162°C. The calculated density is approximately 1.31 g/cm³ under ambient conditions. It is soluble in polar organic solvents such as methanol, ethanol, and dimethyl sulfoxide, moderately soluble in ethyl acetate and dichloromethane, and sparingly soluble in water and nonpolar solvents like hexane. The molecule features a pyridine ring with a hydroxyl group at the 2position, a methyl group at the 6position, and a methyl ester at the 4position. The hydroxyl group can participate in hydrogen bonding and may exist in tautomeric equilibrium with the corresponding pyridone form. The ester is susceptible to hydrolysis under acidic or basic conditions. Storage in tightly sealed containers protected from light and moisture at ambient temperature is generally adequate, though desiccated conditions are recommended for prolonged periods. Contact with strong oxidizing agents, strong acids, and strong bases should be avoided.

Methyl 2-hydroxy-6-methylisonicotinate is a trisubstituted pyridine derivative belonging to the isonicotinic acid family. The molecule combines a phenolic hydroxyl group at the 2position, a methyl substituent at the 6position, and a methyl ester at the 4position of the pyridine ring. The 2hydroxy group can undergo tautomerization to the corresponding 2oxo form, creating an equilibrium that influences both hydrogenbonding capacity and metalchelating ability. The methyl ester provides a protected carboxylic acid handle for further functionalization through hydrolysis, transesterification, or reduction to the corresponding alcohol. The methyl group at the 6position introduces hydrophobic character and steric influence, modulating the overall lipophilicity and binding interactions. This combination of a tautomerizable hydroxyl, a modifiable ester, and an alkyl substituent on a privileged heteroaromatic core makes the compound a valuable building block in medicinal chemistry and organic synthesis for constructing more complex molecules with potential biological activity.

Pharmaceutical Intermediate
In drug discovery, this hydroxypyridine ester is employed as a building block for synthesizing compounds with potential activity against tuberculosis, inflammation, and metabolic disorders. The 2hydroxy group can engage in hydrogen bonding with enzyme active sites, while the ester enables convenient amide coupling with aminecontaining pharmacophores after hydrolysis. The methyl group can influence metabolic stability and binding affinity through hydrophobic interactions. Derivatives of isonicotinic acid, including this compound, are structurally related to isoniazid, a firstline antituberculosis agent.

Building Block for Heterocyclic Systems
The compound serves as a precursor for constructing fused heterocycles such as pyrido[2,3d]pyrimidines, pyrazolo[3,4b]pyridines, and oxazolo[4,5b]pyridines through cyclocondensation reactions. The hydroxyl group can be alkylated or acylated to introduce additional functionality, while the ester provides a handle for further elaboration. These ring systems are investigated for their pharmacological properties, with the rigid pyridine core providing conformational constraint beneficial for target recognition.

Ligand for Metal Complexes
The 2hydroxy group and the pyridine nitrogen can coordinate to transition metals, forming complexes with welldefined geometries. The tautomeric equilibrium between hydroxy and oxo forms can influence the binding mode and stability of metal complexes. Metal complexes derived from this scaffold are studied for their catalytic activity in oxidation and crosscoupling reactions, as well as for their potential as models for metalloenzyme active sites where nitrogen and oxygen donors cooperate in metal coordination.

Organic Synthesis Building Block
As a versatile synthetic intermediate, methyl 2-hydroxy-6-methylisonicotinate participates in diverse transformations including Oalkylation, Oacylation, and palladiumcatalyzed crosscoupling reactions after conversion of the hydroxyl to a triflate or halide. The ester can be reduced to the corresponding alcohol for further functionalization or hydrolyzed to the carboxylic acid for amide coupling. The methyl group provides a site for radical or metalcatalyzed C–H functionalization. Its utility extends to the synthesis of natural product analogs and functional materials where the combination of a tautomerizable hydroxyl and a modifiable ester provides opportunities for controlled molecular elaboration.