Design, Green Synthesis and in silico Studies of New Substituted Naphtho[1,2-e][1,3]Oxazines as Potential Acetylcholinesterase Inhibitors.

Alzheimer's disease (AD) is a prevalent neurodegenerative condition characterized by progressive cognitive decline and memory impairment resulting from the degeneration and death of brain neurons. Acetylcholinesterase (AChE) inhibitors as the primary pharmacotherapy for numerous neurodegenerative conditions, leveraging their capacity to modulate acetylcholine levels crucial for cognitive function. Recently, oxazine and its derivatives have brought worthy synthetic interest due to their extensive biological activities including, anti-acetylcholinesterase, anti-oxidant, anti-pyretic, anti-tubercular, anti-convulsant, anti-microbial, anti-malarial, and anti-cancer activities. In this study, a series of novel naphtho[1,2-e][1,3]oxazine derivatives has been designed and synthesized with potential of acetylcholinesterase (AChE) inhibition. The target products have been prepared by a one-pot and three-component condensation reaction of 2-naphthol, various aromatic aldehydes, and arylmethanimine in the presence of 3-methyl-1-sulfonic acid imidazolium chloride ([Msim]Cl) as an effective and recyclable ionic liquid catalyst under microwave irradiation solvent-free condition. The chemical structures of all resulting products were confirmed by spectroscopic methods (IR, 1H-NMR, 13C NMR) as well as elemental analysis. The molecular docking studies has also been performed to investigate the synthetic compounds in the the AChE active site gorge. The results showed that all these derivatives interact with the enzymes with high affinity in binding pocket. The MM-GBSA studies were performed for all synthesized derivatives and among them, compound 3-(4-Chlorophenyl)-1-phenyl-2,3-dihydro-1H-naphtho[1,2-e][1,3]oxazine 5f, showed the lowest the binding free energy (-48.04 kcal mol-1). In general, oxazine derivatives could be proposed as the strong AChE inhibitors.

Facile, efficient and one-pot access to diverse new functionalized aminoalkyl and amidoalkyl naphthol scaffolds via green multicomponent reaction using triethylammonium hydrogen sulfate ([Et3NH][HSO4]) as an acidic ionic liquid under solvent-free conditions.

An efficient, clean and one-pot multicomponent synthesis of divers kind of new functionalized aminoalkyl naphthol and amidoalkyl naphthol derivatives via tandem condensation reaction of 2-naphthol, aromatic aldehydes and 5-methyl-1,3,4-thiadiazol-2-amine/5-aryl-1,3,4-thiadiazol-2-amines urea/acetamide under solvent-free conditions is reported. Following this protocol, it was possible to synthesize novel 1-(((5-methyl-1,3,4-thiadiazol-2-yl)amino)(aryl)methyl)naphthalen-2-ol, 1-(aryl((5-aryl-1,3,4-thiadiazol-2-yl)amino)methyl)naphthalen-2-ol and amidoalkyl naphthol derivatives. This protocol includes some salient features, such as the use of triethylammonium hydrogen sulfate ([Et3NH][HSO4]) ionic liquid as a green, clean and reusable catalyst, no column chromatographic separation, high atom economy, good yields, low cost and finally no need for a complex procedure.