Bioactivity of a family of chiral nonracemic aminobenzylnaphthols towards Candida albicans

Synthesis, Computational, and Anticancer In Vitro Investigations of Aminobenzylnaphthols Derived from 2-Naphtol, Benzaldehydes, and α-Aminoacids via the Betti Reaction

Multicomponent reactions have emerged as an important approach for the synthesis of diverse and complicated chemical compounds. They have various advantages over two-component reactions, including the convenience of one-pot procedures and the ability to modify the structure of agents. Here, we employed in vitro and in silico studies to explore the anticancer potential of novel aminobenzylnaphthols derived from the Betti reaction (MMZ compounds). MTT assay was used to explore the cytotoxic activity of the compounds in pancreatic (BxPC-3 cells) and colorectal (HT-29) cancer cell lines or normal human lung fibroblasts (WI-38 cells). Proapoptotic properties of two derivatives MMZ-45AA and MMZ-140C were explored using AO/EB and annexin V-FITC/PI staining. In silico studies including ADMET profiling, molecular target prediction, docking, and dynamics were employed. The compounds exhibited cytotoxic properties and showed proapoptotic properties in respective IC50 concentrations. As indicated by in silico investigations, anticancer activity of MMZs can be attributed to the inhibition of ADORA1, CDK2, and TRIM24. Furthermore, compounds exhibited favorable ADMET properties. MMZs constitute an interesting scaffold for the potential development of new anticancer agents.

(S,S)-2-(((Hydroxynaphth-1-yl)(4′-nitrophenyl)methyl)amino)-3-methylbutanoic Acid Methyl Ester

The solvent-free Betti reaction of 2-naphthol, 4-nitrobenzaldehyde and (S)-valine methyl ester gave the corresponding aminobenzylnaphthol of the (S,S)-2-(((hydroxynaphth-1-yl)(4′-nitrophenyl)methyl)amino)-3-methylbutanoic acid methyl ester in good yield (59%). This product was fully characterized. We observed that the racemization that occurs in some Betti reactions with (S)-valine methyl ester was absent in this reaction, and thus the predominant (S,S)-product was obtained.

(S,S)-1-(Phenyl((1′-4-nitrophenyl-ethyl)amino)methyl)-2-naphthol

The Betti reaction of 2-naphthol, benzaldehyde and (S)-1-(4-nitrophenyl)ethylamine without any solvent gave the corresponding aminobenzylnaphthol, that is the (S,S)-1-(phenyl((1′-4-nitrophenyl-ethyl)amino)methyl)-2-naphthol, in good yield (56%). The absolute configuration of the title compound was attributed by NMR analysis, a procedure that is reliable if compared with the data obtained by X-ray diffraction experiments.

Antiproliferative Activity of Aminobenzylnaphthols Deriving from the Betti Reaction

Two aminobenzylnaphthols, which are representative items of the family of compounds synthesized with the Betti reaction, were investigated as antiproliferative agents against adenocarcinoma human colorectal (Caco-2) and human neuroblastoma (SH-SY5Y) cell lines, using cisplatin as a positive control. A better antiproliferative activity was recorded after 24 h of incubation for the first tested molecule, whereas the other one was more effective after 72 h of incubation. These results support the hypothesis that both of the tested aminobenzylnaphthols could potentially be endowed with a biological activity.

A combined structural and computational investigation of aminobenzylnaphthol compounds derived from the Betti reaction using valine methyl ester

We report CH⋯π interactions in aminobenzylnaphthol compounds that bear halogen atoms and amino acid residues (Hirshfeld surface/de, halogen = chlorine).

Estrone derived 2-naphthol analogue in the diastereoselective one-pot Betti-condensation

The utility of deoxy-isoequilenine synthesized from estrone as valuable 2-naphthol analogue is demonstrated in the three components Betti-condensation. A simple, efficient and green procedure for the synthesis of aminobenzylnaphthol analogues (so-called Betti bases) has been realized highly diastereoselectively by using (S)-phenylethylamine and 1- or 2-naphthaldehyde. The absolute configuration of the new chiral compounds obtained has been determined by means of NMR experiments and confirmed by X-ray crystallography. The chiral steroidal aminobenzylnaphthols have been evaluated as pre-catalysts for the addition of diethylzinc to aldehydes with enantioselectivities of up to 98% ee.

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.

Structural insights into methyl- or methoxy-substituted 1-(α-aminobenzyl)-2-naphthol structures: the role of C-H...π interactions

Aminobenzylnaphthols are a class of compounds containing a large aromatic molecular surface which makes them suitable candidates to study the role of C-H...π interactions. We have investigated the effect of methyl or methoxy substituents on the assembling of aromatic units by preparing and determining the crystal structures of (S,S)-1-{(4-methylphenyl)[(1-phenylethyl)amino]methyl}naphthalen-2-ol, C₂₆H₂₅NO, and (S,S)-1-{(4-methoxyphenyl)[(1-phenylethyl)amino]methyl}naphthalen-2-ol, C₂₆H₂₅NO₂. The methyl group influenced the overall crystal packing even if the H atoms of the methyl group did not participate directly either in hydrogen bonding or C-H...π interactions. The introduction of the methoxy moiety caused the formation of new hydrogen bonds, in which the O atom of the methoxy group was directly involved. Moreover, the methoxy group promoted the formation of an interesting C-H...π interaction which altered the orientation of an aromatic unit.

Stacked aryl groups in P-resolved cyclic phosphonamides as a new conformational constraint

π–π stacking as a conformational constraint in the P-resolved cyclic phosphonamides.