Sodium 1,3-oxazole-2-carboxylate
[CAS# 1255098-88-4]

Identification

• Classification: Organic raw materials >> Carboxylic compounds and derivatives
• Name: Sodium 1,3-oxazole-2-carboxylate
• Molecular Formula: C₄H₂NNaO₃
• Molecular Weight: 135.05
• CAS Registry Number: 1255098-88-4
• EC Number: 827-630-6
• SMILES: C1=COC(=N1)C(=O)[O-].[Na+]

Safety Data

• Hazard Symbols: GHS07 Warning
• Hazard Statements: H303-H315-H319-H335
• Precautionary Statements: P261-P264-P264+P265-P271-P280-P301+P317-P302+P352-P304+P340-P305+P351+P338-P319-P321-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	5	H303
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2A	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335

Discovory and Applicatios

Sodium 1,3-oxazole-2-carboxylate is an organic heterocyclic salt derived from oxazole-2-carboxylic acid. Its structure consists of a five-membered aromatic oxazole ring bearing a carboxylate group at the 2-position, neutralized by a sodium cation. The oxazole ring contains both nitrogen and oxygen as heteroatoms, giving the molecule characteristic reactivity and enabling its use as a versatile intermediate in heterocyclic and medicinal chemistry. The sodium salt form increases polarity and aqueous solubility, which can be advantageous in base-mediated reactions or when used as a starting material for further derivatization.

The discovery and development of oxazole-2-carboxylic acid derivatives are closely linked to studies of azole heterocycles throughout the twentieth century. Synthetic studies demonstrated that carboxylation at the C-2 position of oxazoles could be achieved via directed C–H activation or metalation strategies. The sodium salt form became a convenient isolable variant, allowing researchers to handle and store the compound more easily than the free acid in certain situations. As interest in nitrogen- and oxygen-containing heterocycles grew within pharmaceutical chemistry, oxazole-based carboxylates gained attention as stable, functionalized building blocks.

Sodium 1,3-oxazole-2-carboxylate is particularly useful because the carboxylate function can undergo well-established transformations, such as conversion to esters, amides, or acid chlorides. These reactions provide routes to families of oxazole derivatives that have been examined for biological activity or incorporated into more complex scaffolds. Within the oxazole moiety, the heteroatoms influence electron density and direct substitution patterns, allowing additional functionalization or participation in ring-forming reactions. In synthetic methodology research, oxazole-2-carboxylates have been employed in C–H functionalization, annulation strategies, and decarboxylative processes. The latter transformation, in particular, has proven valuable because thermal or catalytic decarboxylation can provide access to substituted oxazole species that would be more difficult to obtain through alternative methods.

Applications of oxazole-2-carboxylate derivatives extend into coordination chemistry. The combined presence of a heterocyclic donor and a carboxylate group allows these molecules to behave as ligands capable of coordinating through the heteroatom or the carboxylate oxygen atoms. In some cases, this coordination results in mononuclear complexes, whereas in others, the carboxylate can act as a bridging group, leading to polymeric or multinuclear assemblies. These complexes have been explored for their structural properties and, in some instances, catalytic activity. The sodium salt provides a convenient starting material for the preparation of additional metal complexes by metathesis or ligand-exchange routes.

In materials and medicinal chemistry, oxazole-2-carboxylates have been investigated as fragments for constructing libraries of heterocyclic molecules. The aromaticity and heteroatom arrangement of the oxazole ring can contribute to binding interactions, while the 2-carboxylate position offers a reliable site for derivatization. As research into heterocycles has expanded, the importance of functionalized azoles such as oxazole-2-carboxylates has been repeatedly demonstrated in synthetic methodology, coordination chemistry, and molecular design.

Although sodium 1,3-oxazole-2-carboxylate itself is mainly used as a precursor rather than a final-use chemical, its availability and well-characterized reactivity make it a valuable reagent in exploratory heterocyclic synthesis. Work involving this compound typically follows standard laboratory precautions for handling organic salts, including protection from moisture when appropriate and avoidance of strong acids that could liberate the free acid form.

References


Yamada K, Kamimura N, Kunishima M (2017) Development of a method for the synthesis of 2,4,5-trisubstituted oxazoles composed of carboxylic acid, amino acid, and boronic acid. Beilstein Journal of Organic Chemistry 13, 1478–1485. DOI: 10.3762/bjoc.13.146


Chavan LN, Pashikanti G, Goodman MM, Liebeskind LS (2025) Rapid and scalable synthesis of oxazoles directly from carboxylic acids. Journal of Organic Chemistry 90(10), 3727–3732. DOI: 10.1021/acs.joc.4c03166


Verrier C, Martin T, Hoarau C, Marsais F (2008) Palladium-catalyzed direct (hetero)arylation of ethyl oxazole-4-carboxylate: an efficient access to (hetero)aryloxazoles. Journal of Organic Chemistry 73, 7383–7386. DOI: 10.1021/jo801093n