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We report the first regioselective C2-C7 oxidative coupling of indoles using a palladium catalyst upon the strategic installation of N-pyri-dinyl and C3-carbonyl, which delivers 2,7-biindoles with a broad scope (25 examples; up to 93% yield). Isolation of the catalytic intermediate reveals the initial activation of the C(7)-H bond, followed by the C(2)-H bond in indoles, and the reaction proceeds via a Pd(II)/Pd(0) pathway. [ABSTRACT FROM AUTHOR]

Chemoselective hydrogenation of α,β‐epoxy ketones and α‐ketoamides is achieved at room temperature (25 °C) using 2.0 bar H2 and a pincer‐ligated Mn(I) catalyst that provides synthetically valuable α‐hydroxy epoxides and α‐hydroxy amides. This protocol applies to a wide range of alkyl‐ and aryl‐substituted α,β‐epoxy ketones, including terpenes (α‐ionone, nootkatone, and R‐carvone)‐ and steroids (testosterone and progesterone)‐derived epoxy ketones, and tolerates H2 sensitive functionalities, such as halides, acetyl, nitrile, nitro, epoxide, alkenyl and alkynyl groups. Additionally, α‐ketoamides bearing reducible functional groups, including acetyl and diazo benzene, were untouched under this protocol and selectively converted to α‐hydroxy amides. A preliminary mechanistic study highlighted the metal‐ligand cooperative H2 activation process. [ABSTRACT FROM AUTHOR]

The development of sustainable protocols for the synthesis of alkylated heteroarenes is crucial owing to their widespread existence in medicinally relevant and bioactive natural products. Herein, we describe an efficient, additive‐ and solvent‐free approach for the regioselective C−H alkylation of indoles and azoles with alkenes using a nickel catalyst, which proceeds through a chelation‐assistance strategy. The reaction exclusively provided branched alkylated products with the compatibility of alkyl, alkoxy, fluoro, trifluoromethyl, alkene, cyano, ester, and carbonyl groups. This protocol is applicable to other heteroarenes, such as imidazoles and benzimidazoles, providing the desired alkylated products with exclusive Markovnikov selectivity. The synthetic utility and scale‐up of the reaction are demonstrated, and the protocol is in concord with the principles of green chemistry. Alkylation proceeds through facile and reversible C−H nickelation and alkene insertion processes, presumably involving rate‐limiting reductive elimination. [ABSTRACT FROM AUTHOR]

An iron‐catalyzed protocol for the synthesis of 3‐amino‐3‐aminomethyl‐2‐oxindole heterocyclic structures is disclosed employing isatins and non‐nucleophilic N‐methoxybenzamides. This reaction class is associated with broad scope and tolerates numerous functionalities, such as fluoro, chloro, bromo, iodo, trifluoromethyl, nitrile, ester, ether, and alkenyl, including heteroaryl – thiophene, benzothiophene, carbazolyl, indolyl, eugenol, and polycyclic cholesterol moieties. Detailed mechanistic investigations reveal that the reaction proceeds via iron‐catalyzed N−O bond cleavage in N‐methoxybenzamides, generating formaldehyde and benzamide, and through the intermediacy of isatin‐ketimines and N‐(hydroxymethyl)benzamides. Overall, this amidation reaction involves one C−C and two C−N bond‐forming tandem processes, providing a range of β‐amino‐aminomethyl‐oxindoles (45 examples) in up to 88% yields. [ABSTRACT FROM AUTHOR]

Developing simple and benign protocols for synthesizing alkenylboronates is crucial as they are synthetically valuable compounds in various organic transformations. In this work, we report a straightforward ligand‐free protocol for synthesizing alkenylboronates via atom‐economical hydroboration of alkynes with HBpin catalyzed by a manganese salt. The reaction shows a high level of chemo and regioselectivity for the terminal alkynes and exclusively produces E‐selective alkenylboronates. The hydroboration scope is vast, with the resilience of a range of synthetically beneficial functionalities, such as halides, ether, alkenyl, silyl and thiophenyl groups. This reaction proceeds through the involvement of a metal‐hydride intermediate. The developed alkenylboronate can be smoothly converted to useful C‐C, C‐N and C‐I bond‐forming reactions. [ABSTRACT FROM AUTHOR]

Alkylated indoles are important motifs in various biologically active molecules and drug candidates. Herein, we report a mild and efficient iron-catalyzed protocol for synthesizing alkylated indoles via C–H bond alkylation of indoles with unactivated alkenes, demonstrating a high level of regioselectivity. The reaction occurs under additive-free, solvent-free (or trace green solvent, 2-MeTHF) and less energy-intensive conditions using a sustainable metal catalyst and provides easy access to privileged alkylated indoles with anti-Markovnikov selectivity. Alkylation is compatible with important functionalities, such as fluoro, chloro, trifluoromethyl, alkenyl, ether, thioether, silyl, and siloxane, including heteroaryl, pyridinyl, carbazolyl, and indolyl moieties (45 examples, up to 96% yield). The developed protocol is very simple, straightforward, and fully accords with the principles of green chemistry. A detailed mechanistic investigation manifests the facile indole's C–H activation at the Fe(0) center, reversible 1,2-insertion of the alkene into the Fe–H bond of a metallacycle, and a turnover-limiting reductive elimination. [ABSTRACT FROM AUTHOR]

Direct functionalization of heterocycles is an advanced strategy for diversifying privileged and biorelevant heterocycle-containing molecules. Particularly, use of the most abundant transition metal, iron, as a catalyst makes this process highly cost-effective and sustainable. Recently, some progress has been realized towards the direct functionalization of heterocycles under iron catalysis. Herein, we present the developments in the C–H bond functionalizations and related reactions of various heterocycles by abundant iron salts. This Synpacts is categorized into different sections based on heterocycles being functionalized, and each section is discussed based on the type of reaction catalyzed by iron. 1 Introduction 2 Functionalization of Indoles 2.1 Alkylation 2.2 Alkenylation 2.3 Other Reactions 3 Oxindoles and Isatins 3.1 C–C Bond Formation 3.2 C–Heteroatom Bond Formation 4 Pyridines and Furans 5 Functionalization of Azoles 6 Summary and Outlook [ABSTRACT FROM AUTHOR]

Iron‐catalyzed dimerization of various isatin derivatives is described for the efficient synthesis of 3,3′‐biindolinylidene‐diones (isoindigos). The reaction provides easy access to self‐coupled and cross‐coupled 3,3′‐indolinylidene‐diones that have high relevance to biology and materials. This Fe(0)‐ or Fe(II)‐catalyzed dimerization reaction tolerates a wide range of functionalities, such as fluoro, chloro, bromo, alkenyl, nitrile, ether, ester, pyrrolyl, indolyl and carbazolyl groups, including cyclic and acyclic alkyls as well as an alkyl‐bearing fatty‐alcohol moiety. Especially, the coupling between two distinct isatins provided excellent selectivity for the cross‐dimerization with trace of self‐couplings. The single‐crystal X‐ray diffraction study established the molecular structure of eight dimerized products. A preliminary mechanistic study of the Fe‐catalyzed dimerization supported the radical pathway for the reaction. [ABSTRACT FROM AUTHOR]

Catalytically active palladium(II) complexes are synthesized by oxidizing the phosphorous centers with a proper amount of water from the 1:1 and 1:2 reactions of aminobis(phosphonite) and palladium precursor, where the thioether-phosphonate moiety has formed a metallacycle containing a metal-phosphorous [sigma] bond. These palladium complexes are shown to be very good catalysts for the Suzuki-Miyaura and Mizoroki-Heck cross-coupling and amination reactions with very good turnover numbers.

The synthesis and characterization of a new class of mixed P,S-mesocyclic ligands and their Pd(II) and Pt(II) complexes is reported. It is demonstrated that the palladium(II) complexes of these new ligands exhibit a significant catalytic activity in the Suzuki-Miyaura cross-coupling reaction.

Selective C(sp2)−H bond alkylation of indoline, carbazole and (2‐pyridinyl)arenes with unactivated alkyl bromides is achieved using MnBr2 catalyst in the absence of an external ligand. The alkylation uses a simple LiHMDS base and avoids the necessity of Grignard reagent, unlike other Mn‐catalyzed C−H functionalization. This reaction proceeded either through a five‐ or a less‐favored six‐membered metallacycle, and tolerated diverse functionalities, including alkenyl, alkynyl, silyl, aryl ether, pyrrolyl, indolyl, carbazolyl and alkyl bearing fatty alcohol and polycyclic‐steroid moieties. Alkylation follows a single electron transfer (SET) pathway involving 1e oxidative addition of alkyl bromide and a rate‐limiting C−H metalation. [ABSTRACT FROM AUTHOR]