Design, synthesis, and evaluation of new benzimidazole‏ ‏‎thiourea ‎derivatives as antitumor agents

Novel benzimidazole thiourea derivatives were designed and synthesized based on sorafenib as a lead compound. The benzimidazole moiety was traded by the pyridine ring to enhance the hydrophobic interaction and retain hydrogen bonding in the hinge region, while lipophilic moieties with different bulkiness were employed in the deep hydrophobic pocket for better hydrophobic interactions. Thiourea as a urea bioisostere was also utilized. Substantial activity was demonstrated against a leukemia subpanel in an in vitro antitumor screening at the NCI. In the single-dose assay, compounds 7i, 7j, and 7l had a GI%) higher than sorafenib against most leukemia cell lines (GI% = 86.2%-137.1%), while in the five-dose assay, compound 7l outperformed sorafenib against the HL-60(TB) and SR leukemia cell lines in terms of GI50 , TGI, and LC50 . Compound 7l also caused cycle arrest at the G0-G1 and S phases in the HL-60(TB) leukemia cell line and induced apoptosis via elevating the Bax/Bcl-2 ratio and increasing caspases 3, 7, and 9 by 5.1-, 3.2-, and 5.2-fold, respectively. Compounds 7i, 7j, and 7l also inhibited the vascular ‎endothelial growth factor receptor-2 (VEGFR-2), B-Raf(V600E) , and platelet-derived growth factor receptor ‎beta (PDGFR-β) enzymes with an IC50 range of 0.063-0.44 μM. COMPARE analysis and a molecular docking study were also performed to predict the possible mechanism of action and binding mode, respectively.

Cascade Reaction of Tertiary Enaminones, KSCN, and Anilines: Temperature-Controlled Synthesis of 2-Aminothiazoles and 2-Iminothiazoline

A one-pot cascade strategy for the synthesis of 2-aminothiazole derivatives by tertiary enaminones, KSCN, and anilines was developed. By changing the reaction temperature, the three-component reaction could be transformed in different ways to obtain moderate to good yields of polysubstituted 2-aminothiazoles and 2-iminothiazolines. This protocol provides an efficient and concise approach to accessing 2-aminothiazole derivatives with potential bioactivity from readily accessible building blocks and reagents.

Recent Advances in the Synthesis of Isothiocyanates Using Elemental Sulfur

Isothiocyanates (ITCs) are biologically active molecules found in several natural products and pharmaceutical ingredients. Moreover, due to their high and versatile reactivity, they are widely used as intermediates in organic synthesis. This review considers the best practices for the synthesis of ITCs using elemental sulfur, highlighting recent developments. First, we summarize the in situ generation of thiocarbonyl surrogates followed by their transformation in the presence of primary amines leading to ITCs. Second, carbenes and amines afford isocyanides, and the further reaction of this species with sulfur readily generates ITCs under thermal, catalytic or basic conditions. Additionally, we also reveal that in the catalyst-free reaction of isocyanides and sulfur, two—until this time overlooked and not investigated—different mechanistic pathways exist.