Synthesis and Anti-Trypanosoma cruzi Biological Evaluation of Novel 2-Nitropyrrole Derivatives

Human American trypanosomiasis, called Chagas disease, caused by T. cruzi protozoan infection, represents a major public health problem, with about 7000 annual deaths in Latin America. As part of the search for new and safe anti-Trypanosoma cruzi derivatives involving nitroheterocycles, we report herein the synthesis of ten 1-substituted 2-nitropyrrole compounds and their biological evaluation. After an optimization phase, a convergent synthesis methodology was used to obtain these new final compounds in two steps from the 2-nitropyrrole starting product. All the designed derivatives follow Lipinski’s rule of five. The cytotoxicity evaluation on CHO cells showed no significant cytotoxicity, except for compound 3 (CC₅₀ = 24.3 µM). Compound 18 appeared to show activity against T. cruzi intracellular amastigotes form (EC₅₀ = 3.6 ± 1.8 µM) and good selectivity over the vero host cells. Unfortunately, this compound 18 showed an insufficient maximum effect compared to the reference drug (nifurtimox). Whether longer duration treatments may eliminate all parasites remains to be explored.

Palladium/Norbornene Cooperative Catalysis

Palladium/norbornene cooperative catalysis has emerged as a distinct approach to construct polyfunctionalized arenes from readily available starting materials. This Review provides a comprehensive overview of this field, including the early stoichiometric investigations, catalytic reaction developments, as well as the applications in the syntheses of bioactive compounds and polymers. The section of catalytic reactions is divided into two parts according to the reaction initiation mode: Pd(0)-initiated reactions and Pd(II)-initiated reactions.

Alkylating Reagents Employed in Catellani-Type Reactions

The Catellani reaction is a powerful strategy that allows the expeditious synthesis of highly substituted arenes, which are not easily accessible through traditional transition-metal-catalyzed cross-coupling reactions. This reaction utilizes the synergistic interplay of palladium and norbornene catalysis to facilitate sequential ortho-C-H functionalization and ipso termination of aryl iodides in a single operation. Since pioneering work by the group of Catellani in 1997, and later by the group of Lautens, this chemistry has attracted considerable attention from the synthetic chemistry community. Dramatic progress has been made by a number of groups in the past two decades. In this Minireview, the alkylating reagents employed in this intriguing reaction and the corresponding applications in organic synthesis are summarized; thus complementing existing reviews to inspire future developments.

Modular One-Step Three-Component Synthesis of Tetrahydroisoquinolines Using a Catellani Strategy

Reported is a modular one-step three-component synthesis of tetrahydroisoquinolines using a Catellani strategy. This process exploits aziridines as the alkylating reagents, through palladium/norbornene cooperative catalysis, to enable a Catellani/Heck/aza-Michael addition cascade. This mild, chemoselective, and scalable protocol has broad substrate scope (43 examples, up to 90 % yield). The most striking feature of this protocol is the excellent regioselectivity and diastereoselectivity observed for 2-alkyl- and 2-aryl-substituted aziridines to access 1,3-cis-substituted and 1,4-cis-substituted tetrahydroisoquinolines, respectively. Moreover, this is a versatile process with high step and atom economy.

A new synthetic approach to the imidazo[1,5-a]imidazole-2-one scaffold and effective functionalization through Suzuki–Miyaura cross coupling reactions

A pathway to new 7-bromo-1-(4-methoxybenzyl)-5-methyl-imidazo[1,5-a]imidazole-2-one was reported. The synthetic potential of this scaffold was demonstrated by displacing bromine by Suzuki–Miyaura cross-coupling reactions.

Synthesis and pharmacological evaluation of M4 muscarinic receptor positive allosteric modulators derived from VU10004

The M4 mAChR is implicated in several CNS disorders and possesses an allosteric binding site for which ligands modulating the affinity and/or efficacy of ACh may be exploited for selective receptor targeting. We report the synthesis of a focused library of putative M4 PAMs derived from VU10004. These compounds investigate the pharmacological effects of target thieno[2,3-b]pyridines assembled from primary cycloalkanamines and cyclic secondary amines providing useful estimates of affinity (KB), cooperativity (αβ), and direct agonist properties (τB).

Synthesis and cytotoxicity of thieno[2,3-b]pyridine and furo[2,3-b]pyridine derivatives

Forty seven thieno[2,3-b]pyridines-2-carboxamides, furo[2,3-b]pyridines-2-carboxamides and tetrahydrothieno[2,3-b]quinolones-2-carboxamides derivatives were synthesized and tested for their antiproliferative activity against the NCI-60 cell lines. The 5-keto-tetrahydrothieno[2,3-b]quinolones-2-carboxamides (series 17) were found to have the greatest activity, with the compound containing a 3-methoxyphenylcarboxamide (compound 17d) being the most active, with GI50 values in the low nanomolar range against a range of cell lines, in particular the melanoma cell line MDA-MD-435 (GI50 - 23 nM) and the breast cancer cell line MDA-MB-468 (GI50 - 46 nM). Molecular modelling of series 17 against phosphoinositide specific-phospholipase C reveals that the side chains of the amino acids His356, Glu341, Arg549 and Lys438 are involved in hydrogen bonding with the ligands as well as a lipophilic pocket is occupied by the phenyl carboxamide moiety.

Diversity-oriented approach to 1,2-dihydroisoquinolin-3(4H)-imines viacopper(i)-catalyzed reaction of (E)-2-ethynylphenylchalcone, sulfonyl azide and amine

A three-component reaction of (E)-2-ethynylphenylchalcone, sulfonyl azide, and amine catalyzed by copper(i) chloride generates 1,2-dihydroisoquinolin-3(4H)-imines in good to excellent yields.