Activated Fuller’s earth: an efficient, inexpensive, environmentally benign, and reusable catalyst for rapid solvent-free synthesis of 1-(amido/amino)alkyl-2-naphthols

Synthesis, biological evaluation, theoretical calculations, QSAR and molecular docking studies of novel arylaminonaphthols as potent antioxidants and BChE inhibitors

A completely green protocol was developed for the synthesis of a series of arylaminonaphthol derivatives in the presence of N-ethylethanolamine (NEEA) as a catalyst under ultrasonic irradiation and solventless conditions. The major assets of this methodology were the use of non-toxic organic medium, available catalyst, mild reaction condition, and good to excellent yield of desired products. All of the synthesized products were screened for their in vitro antioxidant activity using DPPH, ABTS, and Ferric-phenanthroline assays and it was found that most of them are potent antioxidant agents. Also, their butyrylcholinesterase inhibitory activity has been investigated in vitro. All tested compounds exhibited potential inhibitory activity toward BuChE when compared to standard reference drug galantamine, however, compounds 4r, 4u, 4 g and 4x gave higher butyrylcholinesterase inhibitory with IC50 values of 14.78 ± 0.65 µM, 16.18 ± 0.50 µM, 20.00 ± 0.50 µM, and 20.28 ± 0.08 µM respectively. On the other hand, we employed density functional theory (DFT), calculations to analyze molecular geometry and global reactivity descriptors, and MESP analysis to predict electrophilic and nucleophilic attacks. A quantitative structure-activity relationship (QSAR) investigation was conducted on the antioxidant and butyrylcholinesterase properties of 25 arylaminonaphthol derivatives, resulting in robust and satisfactory models. To evaluate their anti-Alzheimer's activity, compounds 4 g, 4q, 4r, 4u, and 4x underwent docking simulations at the active site of the acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), revealing why these compounds displayed superior activity, consistent with the biological findings.

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.

Benzhydryl Amines: Synthesis and Their Biological Perspective

The current review describes the recent progress in the chemistry and biology of the benzhydryl amines where the central carbon atom is directly attached to the nitrogen atom of one ring and which have published in the last five years (2015-2019). Both metal and metal-free racemic and asymmetric synthetic approaches along with their activities as anti-leishmanial, antiviral, antibacterial, and anti-aromatase and other miscellaneous properties are discussed.

Recent advances in the synthesis and synthetic applications of Betti base (aminoalkylnaphthol) and bis-Betti base derivatives

The multicomponent reaction between 2-naphthol, arylaldehydes and ammonia yields aminobenzylnaphthols in a process known as the Betti reaction, which was first uncovered at the beginning of the 20th century. Various methods have been reported for the synthesis of aminobenzylnaphthol (Betti base) and bis-Betti base derivatives using various types of naphthols, aromatic amines, heteroaromatic amines, and aliphatic and cyclic amines instead of ammonia or diamines and aliphatic and aromatic aldehydes or dialdehyde compounds under various conditions in recent years. The Betti reaction produces racemic and non-racemic aminobenzylnaphthol ligands. It is also clear that the most important area of application of the non-racemic aminonaphthols prepared in this manner is their use in asymmetric synthesis, either as chiral ligands or as chiral auxiliaries. The functional groups in these Mannich products offer many ring closure possibilities. Some of these products or the starting bifunctional compounds possess biological activity. Herein, we present a selection of the relevant studies on this topic.