Synthesis of Diiodinated Biphenyls and Iodinatedmeta-Terphenyls by Regioselective Suzuki-Miyaura Cross-Coupling Reactions of 5-Substituted 1,2,3-Triiodobenzenes

Efficient and regioselective synthesis of ortho-diiodinated homobenzylic alcohol derivatives: in silico evaluation as potential anticancer IDO/TDO inhibitors

A simple and direct synthesis of 2,6-diiodophenylethanol building blocks through highly regioselective metalation (MIE)/oxirane SN2-type ring opening of 1,2,3-triiodobenzene is described. A significant impact of the nature of the R1 group on the reactivity of the reaction was discovered but not in terms of site-selectivity. The MIE quenching step is easily controlled by the use of slow-reacting electrophiles "oxiranes" providing solely the ortho-diiodinated homobenzylic alcohol derivatives (internal products) in excellent site-selectivity and with stereoretention. The reaction proceeded without any additives to activate the oxiranes and tolerated a wide range of substrates. The reaction of electron-deficient 1,2,3-triiodoarene systems and neutral oxiranes under the optimized conditions provided the highest isolated yields. The reaction is facile, scalable, efficient, general in scope, and generates handy precursors for further chemical manipulation. In silico interaction analysis revealed that compounds 7a, 7p, 7t and 7z established favourable interactions with the receptors IDO and TDO. Moreover, the molecular simulation results revealed stable dynamics, minimal internal fluctuations, tighter packing and more favourable dynamic features. Furthermore, the 7a-IDO reported a TBE of -26.22 ± 0.24 kcal mol-1, 7t-TDO reported a TBE of -46.66 ± 0.27 kcal mol-1, 7p-TDO reported a TBE of -48.02 ± 0.29 kcal mol-1 while 7z-TDO reported a TBE of -48.51 ± 0.28 kcal mol-1. This shows that these compounds potentially interact with IDO and TDO and consequently cause the inhibition of these targets. Moreover, the BFE results also revealed that this combination suggests that the gas-phase interactions between the components are favorable, but the solvation of the system is unfavorable. In the context of binding, it further means that the protein and ligand have attractive forces when in close proximity as seen in the gas phase, but when solvated, the system experiences an increase in free energy due to interactions with the solvent. This further implies that the binding might be enthalpically favorable due to favorable gas-phase interactions but entropically unfavorable due to unfavorable solvation effects. Our analysis shows that our designed compounds have unmatched pharmacological potential, far surpassing previously reported compounds. This highlights the innovative nature of these derivatives and sets a new benchmark in IDO and TDO drug discovery, indicating their significant potential as effective anticancer inhibitors.

2,5-[C4+C2] Ringtransformation of Pyrylium Salts with α-Sulfinylacetaldehydes

A rapid synthesis of chiral sulfoxide-functionalized meta-terphenyl derivatives by a 2,5-[C4+C2] ring transformation reaction of pyrylium salts with in situ generated enantiomerically pure α-sulfinylacetaldehydes is described in this paper. This synthetic method demonstrates, for the first time, the use of α-sulfinylacetaldehydes in a reaction sequence initiated by the nucleophilic attack of pyrylium salts by α-sulfinylcarbanions to generate chiral aromatic systems. The method presented shows a broad applicability starting with various methyl sulfoxides and a number of functionalized pyrylium salts, furnishing meta-terphenyls with complex substitution patterns from readily accessible starting compounds.

Domino C-C/C-O bond formation: palladium-catalyzed regioselective synthesis of 7-iodobenzo[b]furans using 1,2,3-triiodobenzenes and benzylketones

A facile and efficient synthesis of 7-iodobenzo[b]furan derivatives via a highly regioselective tandem α-arylation/intramolecular O-arylation of 5-substituted-1,2,3-triiodobenzenes and benzylketones is described. Remarkably, the α-arylation coupling reactions initiate exclusively at the least sterically-hindered position of the triiodoarene, which results in a highly chemoselective transformation. The highest yields were observed in reactions between electron-poor 1,2,3-triiodoarenes and electron-rich benzylketones, yet the optimized reaction conditions were found to be tolerant to a wide range of different functional groups. This unprecedent synthesis of 7-iodobenzo[b]furans from 1,2,3-triiodobenzenes is scalable, general in scope, and provides easy access to valuable precursors for other chemical transformations.

Site-Selective Cross-Coupling of Polyhalogenated Arenes and Heteroarenes with Identical Halogen Groups

Methods to functionalize arenes and heteroarenes in a site-selective manner are highly sought after for rapidly constructing value-added molecules of medicinal, agrochemical, and materials interest. One effective approach is the site-selective cross-coupling of polyhalogenated arenes bearing multiple, but identical, halogen groups. Such cross-coupling reactions have proven to be incredibly effective for site-selective functionalization. However, they also present formidable challenges due to the inherent similarities in the reactivities of the halogen substituents. In this Review, we discuss strategies for site-selective cross-couplings of polyhalogenated arenes and heteroarenes bearing identical halogens, beginning first with an overview of the reaction types that are more traditional in nature, such as electronically, sterically, and directing-group-controlled processes. Following these examples is a description of emerging strategies, which includes ligand- and additive/solvent-controlled reactions as well as photochemically initiated processes.

Copper(i)-catalyzed regioselective Ullmann-type coupling of primary carbamates and 5-substituted-1,2,3-triiodobenzenes: facile synthesis of 2,3-diiodinated N-aryl carbamates

Mild, efficient, and unprecedented synthesis of 2,3-diiodinated N-aryl carbamates via highly regioselective Ullmann-type cross-coupling of 5-substituted-1,2,3-triiodobenzene and carbamate.

Heterogeneous Pd/C-catalyzed, ligand free Suzuki-Miyaura coupling reaction furnishes new p-terphenyl derivatives

A series of new para-terphenyls derivatives have been efficiently synthesized by a ligand-free heterogeneous Pd/C-catalyzed two-fold Suzuki-Miyaura coupling reaction. Methyl 5-bromo-2-iodobenzoate was selected to react with a variety of different aryl boronic acids (2a-i). Nine new p-terphenyl derivatives (3a-i) were prepared and the structures were confirmed by several analytical techniques including infrared, spectroscopy, ¹H and ¹³C NMR spectroscopy, mass spectrometry, and in the case of compound 3 b, by X-ray diffraction method. The new derivatives were obtained in very good yields (78-91%). This synthetic facile route is envisioned to improve the preparation of p-terphenyl-based natural products.

Palladium-catalyzed highly regioselective mono and double Sonogashira cross-coupling reactions of 5-substituted-1,2,3-triiodobenzene under ambient conditions

An efficient synthesis of 2,3-diiodinated diphenylacetylene and iodinated meta-terphenylacetylene derivatives through highly regioselective mono and double Sonogashira cross-coupling reactions of 5-substituted-1,2,3-triiodobenzene is reported. Significantly, the regioselectivity of coupling reactions is exclusively performed at the terminal C-I bonds, the less sterically hindered and the most regioactive positions. The highest isolated yields were achieved from reactions of electron-poor/neutral 1,2,3-triiodoarene and electron-rich arylacetylene derivatives. The use of 2.0 equiv. of arylacetylenes in one-pot fashion afforded the iodinated meta-terphenylacetylenes in excellent site selectivity and in good isolated yields. Different functional groups were found to be suitable under optimized conditions. This report discloses the first method to synthesize hitherto unknown 2,3-diiodinated diphenylacetylenes and iodinated meta-terphenylacetylenes that is facile, highly regioselective, general in scope and produces remarkable building blocks for other chemical transformations.

Regioselective synthesis of ortho-iodobiphenylboronic acid derivatives: a superior catalyst for carboxylic acid activation

Efficient and versatile synthesis of ortho-iodobiphenylboronic acids with remarkable catalytic and microbial activities.

Pd-Catalyzed One-Pot Stepwise Synthesis of Benzo[b][1,6]naphthyridines from 2-Chloroquinoline-3-carbonitriles Using Sulfur and Amines As Nucleophiles

A palladium-catalyzed one-pot stepwise coupling-annulation reaction of 2-chloroqunoline-3-carbonitriles enabled the direct synthesis of sulfur-substituted benzo[b][1,6]naphthyridines via multiple bond formation. The reaction provided an unusual mode for cyclization as sodium sulfide, a soft nucleophile, preferred to attack on the carbon of the nitrile group rather than on the C-C triple bond. The developed chemistry was extended with the secondary amines as nucleophiles to afford nitrogen-substituted benzo[b][1,6]naphythyridines while primary amines afforded hydroamination products . The hydromination products were transformed to benzo[b][1,6]naphthyridones via a base-mediated cyclization reaction. The  developed protocol features inexpensive and easily synthesizable starting materials, easy operations, and a high efficiency and tolerance to a broad range of substrates.

Pd-catalyzed one-pot sequential unsymmetrical cross-coupling reactions of aryl/heteroaryl 1,2-dihalides

The present methodology allows the conversion of easily available aryl/heteroaryl 1,2-dihalides into synthetically useful unsymmetrically substituted arenes/heteroarenes in good to excellent yields under mild reaction conditions.