Synthesis and Characterization of Betti Bases Derivatives via Green Mannich Reaction by NS-PCS and FHS as the Catalyst

Zn Complex on Tryptophan-Functionalized MCM-41 as an Efficient and Promising Reusable Nanocatalyst in One-Pot Three-Component Synthesis of Amino Benzyl Quinolinols and Naphthols via a Betti Reaction

In this research, a Zn transition metallic complex on functionalized mesopore silica MCM-41 has been designed and utilized as an effective, recoverable, and thermally stable heterogeneous nanocatalyst in the formation of the C-C bond. Also, the synthesis of amino benzyl quinolinols and amino benzyl naphthol derivatives was performed by the three-component reaction of Betti from aromatic aldehydes, type II amines, and 8-hydroxyquinoline and 1-naphthol in the presence of the MCM-41-tryptophan-Zn nanocatalyst under reflux conditions. The short reaction times, high efficiency of the products, the easy separation of catalysts due to their heterogeneity, and their reusability are the advantages of this method. Finally, the nature of catalysts was studied by using some techniques such as the Fourier transform infrared spectrum, energy-dispersive spectroscopy, hot filtration test, transmission electron microscopy, scanning electron microscopy, X-ray diffraction, inductively coupled plasma optical emission spectrometry, and N₂ adsorption-desorption (BET). The synthesized heterogeneous catalysts showed perfect catalytic activity and also good recyclability in the Betti reaction. They could be reused at least for five consecutive cycles without significant loss of their catalytic activities.

Catalyst-Free Accelerated Three-Component Synthesis of Betti Bases in Microdroplets

Due to their important roles in medicine and asymmetric metal catalysis, the formation of Betti bases has attracted wide interest in organic chemical community. Traditional multicomponent reaction methods for synthesizing Betti bases normally require long reaction times under harsh conditions (high temperature, microwave or ultrasonic irradiation, etc.) in the presence of various catalysts. In this study, we developed a mild, highly efficient and environmentally friendly method to synthesize Betti bases without the use of any catalysts in microdroplets. The Betti reaction was accelerated by 6.53×10³ in microdroplets by comparing the measured rate constant in bulk. Fifteen Betti bases were synthesized by the microdroplet method using a variety of aldehydes, naphthols and amines with 68-98 % yields at a scaled-up amount of 1.9 g h^-1 . Overall it is an attractive alternative to classic organic synthesis for the construction of Betti bases and derivatives.

Recent advances in the green synthesis of Betti bases and their applications: a review

Well-known Betti bases are the products obtained by the one-pot multicomponent reaction of 1-naphthol/2-naphthol, aliphatic/aromatic aldehydes, and secondary amines, and this reaction is known as the Betti reaction. During recent years, due to the unveiling of the pharmacological and synthetic potential of Betti bases, a tremendous increase in the studies reporting novel synthetic methods for the efficient synthesis of Betti bases was observed. This review presents the recent key developments in the green synthesis of the Betti bases and accounts for the significant number of the literature reported during 2019-2022. Both catalyst free as well as the catalyst promoted synthesis (nanocatalyst, biocatalyst, transition metal catalyst, etc.) along with the synthetic applications (catalyst, ligands/chiral auxiliaries, and valuable synthons), optoelectronic applications (fluorescence sensors for phosgene gas, Hg²⁺, and Cr³⁺ detection, quasi-reversible redox potential) and biological properties (anticancer agents, antioxidant, anti-inflammatory agents, antitubercular agents, pesticidal agents, anti-Alzheimer agents, Topoisomerase I inhibitors, YAP-TEAD interaction inhibitors, and DNA binding and cleavage activity) are discussed. There is a surge of interest for the development of the green and efficient Betti reaction for the construction of C-C and C-N bond in a single-step reaction accessing Betti bases as products. Along with key methodological developments for the green synthesis of Betti bases, their applications in synthetic organic chemistry, optoelectronic sensors, advanced materials synthesis, agrochemicals and pharmaceutically active scaffolds, during the period of 2019-2022, have been considered.