Cephalexin (1) was acylated using N-acylbenzotriazoles (3a–k′) derived from various carboxylic acids including aromatic, heterocyclic and N-Pg-α-amino acid to afford N-acylcephalexins in excellent yields (82%–96%). Antibacterial screening of the novel cephalosporins revealed that all targets (4a–j) retained the antibacterial activity of cephalexin against Staphylococcus aureus (ATCC 6538). N-Nicotinylcephalexin (4c) and N-(3,4,5-trimethoxybenzoyl)cephalexin (4g) exhibited a broader spectrum of antibacterial activity towards standard strains of Staphylococcus aureus (ATCC 6538), Paenibacillus polymyxa (ATCC 842), and Escherichia coli (ATCC 10536) as well as a resistant strain of Pseudomonas aeruginosa (ATCC 27853).
Various carboxylic acids were converted into N-acylbenzotriazoles (90-97 % isolated yields) via a one-pot synthesis involving activation of carboxylic acids with tosyl chloride. The novel protocol enabled stepwise manipulation of both carboxylic groups of suberic acid en route to Vorinostate (SAHA). In addition to the high yield of SAHA (84% yield over four steps) the new method comprises a simple work up and short reaction times.
An efficient method for synthesising NMDAR co-agonist Sunifiram (DM235), in addition to Sunifram-carbamate and anthranilamide hybrids, has been developed in high yields
via
protecting group-free stepwise unsymmetric diacylation of piperazine using
N
-acylbenzotiazole. Compounds
3f
,
3d,
and
3i
exhibited promising nootropic activity by enhancing acetylecholine (ACh) release in A549 cell line. Moreover, the carbamate hybrid
3f
was found to exhibit higher
in vitro
potency than donepezil with IC
50
= 18 ± 0.2 nM, 29.9 ± 0.15 nM for
3f
and donepezil, respectively.
3f
was also found to effectively inhibit AChE activity in rat brain (AChE = 1.266 ng/mL) compared to tacrine (AChE = 1.137 ng/ml). An assessment of the ADMET properties revealed that compounds
3f, 3d,
and
3i
are drug-like and can penetrate blood–brain barrier. Findings presented here showcase highly potential cholinergic agents, with expected partial agonist activity towards glycine binding pocket of NMDAR which could lead to development and optimisation of novel nootropic drugs.
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