Modular and Divergent Syntheses of Protoberberine and Protonitidine Alkaloids

Recent advances in controllable/divergent synthesis

The development of streamlined methodologies for the expeditious assembly of structurally diverse organic architectures represents a paramount objective in contemporary synthetic chemistry, with far-reaching implications across pharmaceutical development, advanced materials innovation, and fundamental molecular science research. In recent years, controllable/divergent synthetic strategies for organic functional molecules using common starting materials have garnered significant attention due to their high efficiency. This review categorizes recent literatures focusing on key regulatory factors for product divergent formation, in which controlling chemical selectivity primarily relies on ligands, metal catalysts, solvents, time, temperature, acids/bases, and subtle modifications of substrates. To gain a deeper understanding of the mechanisms underlying reaction activity and selectivity differentiation, the review provides a systematic analysis of the mechanisms of critical steps through specific case studies. It is hoped that the controllable/divergent synthesis concept will spark the interest of practitioners and aficionados to delve deeper into the discipline and pursue novel advancements in the realm of chemical synthesis.

Discovery, synthesis and biological evaluation of novel isoquinoline derivatives as potent indoleamine 2, 3-dioxygenase 1 and tryptophan 2, 3-dioxygenase dual inhibitors

Indoleamine 2,3-dioxygenase (IDO) and tryptophan 2,3-dioxygenase (TDO) play a pivotal role in regulating kynurenine catabolism pathway and immunosuppressive environment, which are promising drug targets for cancer immunotherapy. In this work, a variety of isoquinoline derivatives were designed, synthesized and evaluated for the inhibitory activity against IDO1 and TDO. The enzymatic assay and structure-activity relationship studies led to the most potent compound 43b with IC50 values of 0.31 μM for IDO1 and 0.08 μM for TDO, respectively. Surface plasmon resonance (SPR) revealed direct binding affinity of compound 43b to IDO1 and TDO and molecular docking studies were performed to predict the possible binding mode. Further pharmacokinetic study and biological evaluation in vivo showed that 43b displayed acceptable pharmacokinetic profiles and potent antitumor efficacy with low toxicity in B16-F10 tumor model, which might provide some insights into the discovery of novel IDO1/TDO inhibitors for cancer immunotherapy.

Recent advances in total synthesis of protoberberine and chiral tetrahydroberberine alkaloids

Covering: Up to 2024Due to the widespread distribution of protoberberine alkaloids (PBs) and tetrahydroberberine alkaloids (THPBs) in nature, coupled with their myriad unique physiological activities, they have garnered considerable attention from medical practitioners. Over the past few decades, synthetic chemists have devised various total synthesis methods to attain these structures, continually expanding reaction pathways to achieve more efficient synthetic strategies. Simultaneously, the chiral construction of THPBs has become a focal point. In this comprehensive review, we categorically summarized the developmental trajectory of the total synthesis of these alkaloids based on the core closure strategies of protoberberine and tetrahydroberberine.

An efficient and chemoselective method to generate arynes

Arynes hold immense potential as reactive intermediates in organic synthesis as they engage in a diverse range of mechanistically distinct chemical reactions. However, the poor functional group compatibility of generating arynes or their precursors has stymied their widespread use. Here, we show that generating arynes by deprotonation of an arene and elimination of an "onium" leaving group is mild, efficient and broad in scope. This is achieved by using aryl(TMP)iodonium salts (TMP = 2,4,6-trimethoxyphenyl) as the aryne precursor and potassium phosphate as the base, and a range of arynophiles are compatible. Additionally, we have performed the first quantitative analysis of functional group compatibility for several methods to generate arynes, including the method developed here and the current state of the art. Finally, we show that a range of "sensitive" functional groups such as Lewis and Brønsted acids and electrophiles are compatible under our conditions.

One-Pot Synthesis of Benzo[c]phenanthridine Alkaloids from 7-Azabenzonorbornadienes and Aryl Nitrones

An efficient synthesis of benzo[c]phenanthridine alkaloids via a synergistic combination of C-C bond formation and a cycloaromatization reaction is described. Aryl nitrones react with 7-azabenzonorbornadienes in the presence of a Rh(III) catalyst, providing pharmaceutically useful benzo[c]phenanthridine derivatives in good to moderate yields. Using this methodology, highly useful alkaloids such as norfagaronine, norchelerythrine, decarine, norsanguinarine, and nornitidine were prepared in a single step.

Design, synthesis and mechanism study of novel natural-derived isoquinoline derivatives as antifungal agents

In screening for natural fungicidal leads, two series of novel 3-aryl-isoquinoline derivatives 8 and 9 were designed and synthesized based on sanguinarine, chelerythrine and berberine. Their structures were confirmed by 1D, 2D NMR and HRMS. Most of the title compounds showed medium to excellent antifungal activity in vitro at 50 mg/L, which were much more active than the lead of sanguinarine. Especially, 9f possessed the best effective against Alternaria solani (80.4%), Alternaria alternata (88.2%) and Physalospora piricola (93.8%). Furthermore, the EC₅₀ of 9f (3.651 mg/L) against P. piricola was marginally better than chlorothalonil (3.869 mg/L). In vivo antifungal activity of 9f against P. piricola was studied on apples. The curative and protection results at the dosage of 50 and 100 mg/L showed as 70.45 ~ 81.67% and 64.96 ~ 80.34%, respectively, which were equal to that of chlorothalonil (80.30 ~ 86.67%, 73.08 ~ 76.92%). Molecular electrostatic potential and molecular docking analysis revealed that 9f was fully covered by positive potential contour, which was easier to interact with the negative amino acid resides of succinate dehydrogenase than 8f. 9f could be used as a novel antifungal lead compound for further study. Two series of novel isoquinoline derivatives 8, 9 containing 3-aryl were rational designed and synthesized based on quaternary isoquinoline alkaloids. The bioassay and interaction mechanism studies indicated that 9f should be considered as potential antifungal lead.

Cu/Fe-mediated N(sp2)-arylation/alkenylation of pyridines with aryl-/alkenylboronic acids to yield versatile cationic materials

Cu/Fe-mediated N(sp2)-arylation/alkenylation of pyridines with aryl-/alkenylboronic acids to yield length-controllable and multi-responsive pyridinium salts is disclosed.

Construction of a Protoberberine Alkaloid Skeleton via the Palladium-Catalyzed α-Arylation-Amide Formation Cascade

In this work, we report the strategy of one-pot synthesis of protoberberine alkaloid derivatives via palladium-catalyzed cascade α-arylation and cyclization, which can afford the target molecules in moderate to excellent isolated yields using commercially available raw materials under solvent-free conditions. This protocol provides an efficient and convenient path to multisubstituted protoberberine derivatives. In addition, it can directly afford natural alkaloids.

Vinylcyclopropanes as All-Carbon 1,5-Dipoles: A Reactivity Switch for Palladium-Catalyzed (5 + 4) Cycloadditions

Azonanes were prepared by a palladium-catalyzed (5 + 4) cycloaddition between activated vinylcyclopropanes and 1-azadienes. During this process, the vinylcyclopropane partner displayed an unusual reactivity and behaved as an all-carbon 1,5-dipole. A N,N-bidentate ligand was required to inhibit the formation of thermodynamic (3 + 2) cycloadducts.