Recent advances on synthesis and biological activities of C-17 aza-heterocycle derived steroids

Catalyst- and excess reagent recycling in aza-Michael additions

16α-Azolyl-pregnenolone derivatives were prepared via 2-butyl-1,1,3,3-tetramethylguanidine (n-Bu-TMG) catalysed aza-Michael addition of 16-dehydropregnenolone (16-DHP) carried out in [bmim][BF4]. The application of the guanidine base and the imidazolium ionic liquid made it possible to recycle not only the catalyst/solvent mixture but also the excess of the N-heterocyclic reagent. By the introduction of CO2 at the end of the reaction, both the guanidine base and the unreacted (excess) reagent could be converted into ionic species that remained dissolved in the ionic liquid phase, while the steroid components were extracted with an apolar solvent. After the removal of CO2, the experiment could be repeated by the addition of the steroid substrate and only an equimolar amount of the N-heterocycle. The methodology was successfully applied to a number of N-heterocycles, such as imidazole, pyrazole, 1,2,3- and 1,2,4-triazoles, and benzimidazole. Indazole and indole could also be converted into the corresponding products, but a stronger base had to be used to obtain a recyclable system.

Synthesis and biological activities of bicyclic pyridines integrated steroid hybrid

Reports on structural modification of heterosteroids through various reactions, and developed synthetic routes have considerably increased over the last decade. The present review encompasses the applicable approaches dealing with the utility of reactive moieties in various steroids for the synthesis of fused bicyclic pyridines, and binary bicyclic pyridines all over the years. The different sections include the synthesis of steroids-fused, and binary quinolines, pyridopyrimidines, imidazopyridines, spirocyclic imidazopyridines, pyrazolopyridines, thienopyridines, pyridinyl-thiazoles, and tetrazolopyridine hybrids, as well as, the diverse biological applications of these heterocyclic steroids. The researchers' interest was principally focused on investigating the flexibility of synthetic strategies for various derivatives of natural steroids and building proposals based on heterocyclic steroids for drug discovery, biological assessments, and synthetic applications.

Palladium-Catalyzed Carbonylative Difunctionalization of Unactivated Alkenes Initiated by Unstabilized Enolates

This report describes the first example of palladium-catalyzed carbonylative difunctionalization of unactivated alkenes initiated by enolate nucleophiles. The approach involves initiation by an unstabilized enolate nucleophile under an atmospheric pressure of CO and termination with a carbon electrophile. This process is compatible with a diverse range of electrophiles, including aryl, heteroaryl, and vinyl iodides to yield synthetically useful 1,5-diketone products, which were demonstrated to be precursors for multi-substituted pyridines. A PdI -dimer complex with two bridging CO units was observed although its role in catalysis is not yet understood.

Exploration of NMI-MsCl mediated amide bond formation for the synthesis of novel 3,5-substituted-1,2,4-oxadiazole derivatives: synthesis, evaluation of anti-inflammatory activity and molecular docking studies

We herein report the facile synthesis of a series of 3,5-substituted-1,2,4-oxadiazole derivatives 9a-e and 10a-e in good to excellent yields by employing NMI-MsCl mediated amide bond formation reaction. The anti-inflammatory potential of the newly synthesized compounds were evaluated by anti-denaturation assay using diclofenac sodium as the reference drug. The compounds 9a and 9d demonstrated promising activity profile when compared to the reference standard. The SAR and molecular docking studies were also carried out for obtaining more details about the profound activity profile of the synthesized molecules. The synthesized compounds were docked against two target proteins TGF-β and IL-1 by AutoDock vina and Auto Dock 4.2.

Semi-Synthesis and Biological Evaluation of 25(R)-26-Acetoxy-3β,5α-Dihydroxycholest-6-One

Previously, we identified a series of steroids (1–6) that showed potent anti-virus activities against respiratory syncytial virus (RSV), with IC50 values ranging from 3.23 to 0.19 µM. In this work, we first semi-synthesized and characterized the single isomer of 5, 25(R)-26-acetoxy-3β,5α-dihydroxycholest-6-one, named as (25R)-5, in seven steps from a commercially available compound diosgenin (7), with a total yield of 2.8%. Unfortunately, compound (25R)-5 and the intermediates only showed slight inhibitions against RSV replication at the concentration of 10 µM, but they possessed potent cytotoxicity activities against human bladder cancer 5637 (HTB-9) and hepatic cancer HepG2, with IC50 values ranging from 3.0 to 15.5 µM without any impression of normal liver cell proliferation at 20 µM. Among them, the target compound (25R)-5 possessed cytotoxicity activities against 5637 (HTB-9) and HepG2 with IC50 values of 4.8 µM and 15.5 µM, respectively. Further studies indicated that compound (25R)-5 inhibited cancer cell proliferation through inducing early and late-stage apoptosis. Collectively, we have semi-synthesized, characterized and biologically evaluated the 25R-isomer of compound 5; the biological results suggested that compound (25R)-5 could be a good lead for further anti-cancer studies, especially for anti-human liver cancer.