Palladium-Catalyzed Carbonylative Sonogashira/Annulation Reaction: Synthesis of Indolo[1,2-b]isoquinolines

Palladium-Catalyzed Carbonylative Sonogashira Transformations: Advancements and Insights

Palladium-catalyzed carbonylative reactions, used as a tool for the insertion of carbonyl group into organic moieties, is a synthetically useful transformation. Carbonylative Sonogashira coupling is a convenient approach for the synthesis of α,β-acetylenic ketones which are important class of molecules in pharmaceutical and industrial fields. Development of greener approaches and environmentally benign catalytic systems put forward enormous opportunities in this field and moreover, these researches indicate the formation of heterocycles via this carbonylation strategy, which is a major highlight. Herein, we discuss the progress achieved in palladium-catalyzed carbonylative Sonogashira coupling from 2013 to 2024 and its future prospects.

Unifying the Absolute Configuration of Dibenzopyrrocoline Alkaloids with Relative Configuration Revision of Cryptowolinol and Description of Isocryptaustoline from Cryptocarya oubatchensis

Dibenzopyrrocoline alkaloids, found in lauraceous and hernandiaceous plants, have been studied since the 1950s. The absolute configuration of these alkaloids, including cryptaustoline, has been a topic of debate due to conflicting studies. Having in our laboratory some authentic samples of dibenzopyrrocoline-type Cryptocarya alkaloids, we decided to reinvestigate their absolute configuration using modern spectroscopic techniques along with TDDFT calculations. The NMR reinvestigation of the authentic sample of cryptowolinol led us to revise its relative configuration using ML-J-DP4 and DP4+ analyses. Moreover, the absolute configuration of all dibenzopyrrocoline alkaloids reported to date benefitted from a complete re-evaluation based on a comparison with TDDFT-SR and TDDFT-ECD predictions leading to a unified absolute configuration. At last, this patrimonial reinvestigation unveiled a historical sample corresponding to a heretofore unpublished dibenzopyrrocoline alkaloid, which we named isocryptaustoline. The reisolation of this molecule from the total alkaloid extract of Cryptocarya oubatchensis makes it a genuine natural product.

Palladium-Catalyzed Cascade Carbonylation Reaction: Synthesis of Fused Isoindolinones

A palladium-catalyzed cascade carbonylation reaction of 2-bromo-N-(2-iodophenyl)benzamides with benzylidenecyclopropanes for the synthesis of fused isoindolinone derivatives has been developed. A broad range of 6/5/6/6 tetracyclic isoindolinone products were efficiently prepared in moderate to good yields with diverse substitution. Two carbonyl groups were incorporated into the substrates in a single step with the formation of four carbon-carbon bonds and two carbon-heteroatom bonds.

Synthesis of Multisubstituted 2,3-Allenamides via Palladium-Catalyzed Carbonylation of Propargylic Esters

2,3-Allenamides are an important class of unsaturated group-substituted carbonyl compounds. A palladium-catalyzed aminocarbonylation of propargyl acetates with amines for the synthesized tri-/tetrasubstituted 2,3-allenamides has been developed. A broad range of tri-/tetrasubstituted 2,3-allenamides have been prepared from propargyl acetates in good to excellent yields. The reaction featured mild reaction conditions and good functional group tolerance. The applicability of this methodology was further highlighted by the late-stage modification of several natural products and pharmaceuticals.

Bro̷nsted Acid-Catalyzed [5+1] and [4+1] Annulation of Cyclic Anhydrides with o-Alkynylanilines to Construct Fused-N-Heterocycles

An unprecedented p-TsOH and MsOH-catalyzed construction of valuable isoindolo/pyrido/pyrrolo-quinolinediones and isoindolo-indolones is demonstrated through annulation reactions of cyclic anhydrides or o-formylbenzoates with o-alkynylanilines. The metal-free Bro̷nsted acid-mediated new [5+1] and [4+1] fused-cyclization is an operationally simple, highly regioselective, atom economical, high yielding, sustainable, and catalytically efficient approach.

Anti-α-Glucosidase, SAR Analysis, and Mechanism Investigation of Indolo[1,2-b]isoquinoline Derivatives

To find potential α-glucosidase inhibitors, indolo[1,2-b]isoquinoline derivatives (1-20) were screened for their α-glucosidase inhibitory effects. All derivatives presented potential α-glucosidase inhibitory effects with IC₅₀ values of 3.44 ± 0.36~41.24 ± 0.26 μM compared to the positive control acarbose (IC₅₀ value: 640.57 ± 5.13 μM). In particular, compound 11 displayed the strongest anti-α-glucosidase activity, being ~186 times stronger than acarbose. Kinetic studies found that compounds 9, 11, 13, 18, and 19 were all reversible mix-type inhibitors. The 3D fluorescence spectra and CD spectra results revealed that the interaction between compounds 9, 11, 13, 18, and 19 and α-glucosidase changed the conformational changes of α-glucosidase. Molecular docking and molecular dynamics simulation results indicated the interaction between compounds and α-glucosidase. In addition, cell cytotoxicity and drug-like properties of compound 11 were also investigated.

Transition-Metal-Catalyzed Carbonylative Multifunctionalization of Alkynes

Currently, the construction of new carbon-carbon bonds and value-added structures in an atom- and step economical manner has become a continuous pursuit in the synthetic chemistry community. Since the first transition-metal-catalyzed hydroformylation of ethylene was reported by Otto Roelen in the 1930s, impressive progress has been achieved in the carbonylative functionalization of unsaturated C-C bonds. In contrast to alkenes, the carbonylative functionalization of alkynes offers tremendous potential for the construction of multisubstituted carbonyl-containing derivatives because of their two independently addressable π-systems. This review provides a timely and necessary investigation of transition-metal-catalyzed carbonylative mutifunctionalization of alkynes with the exclusion of carbonylative hydrofunctionalizations. Different transition metals including palladium, rhodium, iridium, ruthenium, iron, copper, etc. were applied to the development of novel carbonylative transformation. Various C-C, C-N, C-O, C-S, C-B, C-Si, and carbon-halogen bonds were formed efficiently and give the corresponding tri- or tetrasubstituted α,β-unsaturated ketones, diesters, and heterocycles.

Pd/Cu catalyzed carbonylation of α-aminoaryl-tethered alkylidenecyclopropanes: synthesis of furoquinoline derivatives

A Pd/Cu catalyzed carbonylation of α-aminoaryl-tethered ACPs for the synthesis of furoquinoline derivatives has been developed. Oxygen was used as the terminal oxidant.