1-methyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-3,4-dihydroquinolin-2(1H)-one
[CAS# 1427587-32-3]

Identification

• Classification: Pharmaceutical intermediate >> Heterocyclic compound intermediate >> Quinoline compound
• Name: 1-methyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-3,4-dihydroquinolin-2(1H)-one
• Molecular Formula: C₁₆H₂₂BNO₃
• Molecular Weight: 287.16
• CAS Registry Number: 1427587-32-3
• EC Number: 139-191-1
• SMILES: B1(OC(C(O1)(C)C)(C)C)C2=CC3=C(C=C2)N(C(=O)CC3)C

Properties

• Density: 1.1±0.1 g/cm³ Calc.^*
• Boiling point: 487.3±45.0 ºC 760 mmHg (Calc.)^*
• Flash point: 248.5±28.7 ºC (Calc.)^*
• Index of refraction: 1.541 (Calc.)^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07 Warning
• Hazard Statements: H302-H315-H319-H335
• Precautionary Statements: P261-P264-P264+P265-P270-P271-P280-P301+P317-P302+P352-P304+P340-P305+P351+P338-P319-P321-P330-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Discovory and Applicatios

1-methyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-3,4-dihydroquinolin-2(1H)-one is a synthetically valuable heterocyclic compound incorporating a boronic ester functionality onto a partially saturated quinolinone scaffold. The compound is notable for its ability to act as a versatile intermediate in the synthesis of complex molecular architectures, particularly in pharmaceutical and materials chemistry.

The core of the molecule is a 3,4-dihydroquinolin-2(1H)-one structure, a bicyclic system composed of a benzene ring fused to a partially saturated pyridone ring. This substructure is commonly found in a variety of bioactive compounds, including alkaloids, enzyme inhibitors, and other pharmacologically relevant molecules. The partial saturation of the quinoline ring at positions 3 and 4 increases molecular flexibility and reduces aromatic character, which can be beneficial in modulating biological activity and solubility.

At the 1-position of the quinolinone ring, a methyl group is introduced. N-methylation enhances the lipophilicity of the molecule and may influence the molecule’s binding affinity to target proteins by altering hydrogen bonding and steric interactions. Methylation also often improves metabolic stability by reducing susceptibility to enzymatic oxidation at the nitrogen center.

A significant feature of this compound is the presence of a boronic ester group at the 6-position of the aromatic ring. Specifically, it bears a 4,4,5,5-tetramethyl-1,3,2-dioxaborolane substituent, which forms a stable five-membered cyclic ester with the boron atom. This group is highly important in synthetic organic chemistry due to its reactivity in palladium-catalyzed Suzuki-Miyaura cross-coupling reactions. Such couplings are widely used to form carbon–carbon bonds between sp²-hybridized centers, enabling the generation of diverse aryl or vinyl derivatives.

The placement of the boronic ester at the 6-position relative to the nitrogen in the heterocyclic ring system provides a strategically useful site for further functionalization without interfering with the lactam functionality. The dioxaborolane ring ensures the boron atom is protected against hydrolysis during many synthetic operations, yet it remains sufficiently reactive under coupling conditions.

From a medicinal chemistry perspective, this compound’s framework is highly amenable to derivatization, making it a promising building block for the development of analog libraries aimed at structure-activity relationship (SAR) studies. The quinolinone moiety, in particular, is a privileged scaffold known to interact with various biological targets, including kinases, GPCRs, and microbial enzymes. Substituents at the 6-position can significantly alter the binding profile and pharmacokinetics of the molecule.

Additionally, the modular nature of this compound makes it useful in the development of small-molecule probes for chemical biology applications. The boronic ester group not only allows for bioconjugation through cross-coupling but may also interact reversibly with diols and hydroxyl-containing biomolecules under aqueous conditions, opening possibilities for sensor or labeling technologies.

In material science, such molecules bearing rigid bicyclic backbones and boron functionalities are being explored for applications in light-emitting diodes, fluorescent tags, and molecular recognition elements. Their ability to be finely tuned through electronic and steric modifications makes them adaptable to various platforms.

Overall, 1-methyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-3,4-dihydroquinolin-2(1H)-one serves as a multifunctional intermediate with broad potential across synthetic chemistry, drug discovery, and material applications. Its stable yet reactive nature allows for a high degree of synthetic manipulation, while its core heterocyclic system provides a well-studied and biologically relevant foundation.