[BPy][OH] Immobilized Hydrotalcite Clay Catalytic System for
1,2-dihyd-roquinazolines Synthesis
Authors: Srivastava Vivek 
Published: July 2023

Abstract:
We easily synthesized two ionic liquids, [BMIM][OH] and [BPy][OH], with high yield. We found that hydrotalcite clay, mediated by these ionic liquids, is a highly effective catalyst for synthesizing biologically active 1,2-dihydroquinazoline derivatives. Using a simple reaction protocol and easy product isolation steps, we successfully synthesized 18 different 1,2-dihydroquinazoline derivatives and were able to recycle the catalysts up to 8 times. Overall, the use of hydrotalcite and [BPy][OH] catalysts provide a more efficient and environmentally friendly method for synthesizing quinazolines compared to traditional methods that often require harsh conditions and toxic reagents.

Background:
1,2-Dihydroquinazolines are an important class of heterocyclic compounds with diverse
biological activities, including anticancer, antifungal, and antibacterial properties. They also exhibit
other pharmacological activities such as antihypertensive, anti-inflammatory, and antiviral effects. The
synthesis of 1,2-dihydroquinazolines dates to the early 20th century when they were first synthesized by
Pictet and Huber in 1911 by the condensation of anthranilic acid with aldehydes or ketones in the presence
of strong acids. Since then, numerous methods have been developed for their synthesis, including
the cyclization of o-aminobenzamides, the reaction of o-aminoaryl ketones with aldehydes or ketones,
and the use of catalysts such as Lewis acids and transition metals. In recent years, the development of
new synthetic methods for the efficient and selective synthesis of 1,2-dihydroquinazolines has been of
great interest to synthetic chemists, particularly in the pharmaceutical industry. These methods include
the use of microwave irradiation, ultrasound, and ionic liquids as green solvents.

:
Overall, the synthesis of 1,2-dihydroquinazolines has been an active area of research, and new methods
continue to be developed to improve their synthesis and properties for various applications.

Methods:
We easily synthesized two ionic liquids, [BMIM][OH] and [BPy][OH], with high yields. We found that hydrotalcite clay, mediated by these ionic liquids, is a highly effective catalyst for synthesizing biologically active 1,2-dihydroquinazoline derivatives.

Results:
Overall, our results provide insights into the development of efficient and sustainable methods for the synthesis of 1, 2-dihydroquinazolines.

Conclusion:
In summary, our studies demonstrated that the [BPy][OH] ionic liquid and hydrotalcite clay catalytic system could be used for the synthesis of various 1, 2-dihydroquinazolines using different aromatic carbonyl compounds, amino benzophenone derivatives, and heterocyclic aldehydes. The presence of electron-donating substituents in the phenyl group provided higher yields than electron-withdrawing groups, and the para position of the aldehyde group had a more significant effect than the ortho or meta position. Our catalytic system was also found to be recyclable for up to eight runs without significant loss of catalytic activity. Overall, our results provide insights into the development of efficient and sustainable methods for the synthesis of 1, 2-dihydroquinazolines.