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A metal‐free heterogeneous protocol is established herein for the synthesis of value‐added γ‐amino acid scaffolds via carbocarboxylation of alkenes with CO2 and alkylamines under visible light irradiation. The protocol shows broad substrate scope under mild reaction conditions and good stability of the catalyst for recycle tests. Moreover, the methodology could be feasible to the late‐stage derivatization of several natural products, enriching the chemical arsenal for practical application. [ABSTRACT FROM AUTHOR]

A sustainable system for the carbocarboxylation of olefins with redox-active esters and CO2via visible-light-induced photoredox catalysis has been developed using metal-free boron carbonitride (BCN) as the photocatalyst. The scheme introduces versatile alkyl groups (including primary, secondary, and tertiary) and CO2 into the C–C double bond in a fully regioselective manner to produce valuable carboxylic derivatives with excellent yields. [ABSTRACT FROM AUTHOR]

Light‐driven fixation of CO2 in organics has emerged as an appealing alternative for the synthesis of value‐added fine chemicals. Challenges remain in the transformation of CO2 as well as product selectivity due to its thermodynamic stability and kinetic inertness. Here we develop a boron carbonitride (BCN) with the abundant terminal B/N defects around the mesoporous walls, which essentially enhances surface active sites as well as charge transfer kinetics, boosting the overall rate of CO2 adsorption and activation. In this protocol, anti‐Markovnikov hydrocarboxylation of alkenes with CO2 to an extended carbon chain is achieved with good functional group tolerance and specific regioselectivity under visible‐light irradiation. The mechanistic studies demonstrate the formation of CO2 radical anion intermediate on defective boron carbonitride, leading to the anti‐Markovnikov carboxylation. Gram‐scale reaction, late‐stage carboxylation of natural products and synthesis of anti‐diabetic GPR40 agonists reveal the utility of this method. This study sheds new insight on the design and application of metal‐free semiconductors for the conversion of CO2 in an atom‐economic and sustainable manner. [ABSTRACT FROM AUTHOR]

A metal-free protocol is established for the decarboxylative N–H or C(sp2)–H functionalization of acids via metal-free boron carbon nitride (BCN) photocatalysis, delivering the desired products under ambient conditions. This methodology is applicable to the late-stage modification of pharmaceutical molecules and gram-scale experiments as well as in the recovery and reuse of the photocatalysts without the loss of reactivity. The developed photochemical reaction system fulfills the requirements of green and sustainable chemistry. [ABSTRACT FROM AUTHOR]

Designing metal‐free catalysts for solar energy conversion is a long‐standing challenge in semiconductor photoredox catalysis (SPC). With visible‐light‐responsive hexagonal boron carbon nitride (h‐BCN) as a non‐metal photocatalyst, this system affords C−H/N−H coupling products with broad substitution tolerance and high efficiency with molecular oxygen as the terminal oxidant. The catalyst exhibits remarkable performance for the selective C−H functionalization of electron‐rich arenes to C−N products (yields up to 95 %) and good stability (6 recycles). Both nitrogen heteroarenes and amine salts are competent coupling nucleophiles. Mechanically, the reactive oxygen species are superoxide anion radical (O2−.) and H2O2, which are proved by electron spin resonance (ESR) data, KI‐starch, and control experiments. In addition, kinetic isotope effect (KIE) experiments indicate that C−H bond cleavage is not involved in the rate limiting step. This semiconductor‐based photoredox system allows for C−H amination free of any metals, ligands, strong oxidants, and additives. It provides a complementary avenue to C−H functionalizations and enables synthetic applications efficiently in a sustainable manner. Oxygen does the trick: Semiconductor photoredox catalysis (SPC) offers a simple and environment‐friendly access to the construction of C−N bonds. This heterogeneous system provides a green route to the selective C−H amination of arenes with molecular oxygen as the only oxidant. [ABSTRACT FROM AUTHOR]

Abstract: An efficient metal‐free catalytic system has been developed based on hexagonal boron carbon nitride (h‐BCN) nanosheets for the dehydrogenation of N‐heterocycles with visible light; hydrogen gas is released in the process, and thus no proton acceptor is needed. This acceptorless dehydrogenation of hydroquinolines, hydroisoquinolines, and indolines to the corresponding aromatic N‐heterocycles occurred in excellent yield under visible‐light irradiation at ambient temperature. With h‐BCN as the photocatalyst and water as the solvent, this environmentally benign protocol shows broad substitution tolerance and high efficiency. [ABSTRACT FROM AUTHOR]

Highly regioselective nucleopalladation for the oxidative coupling of internal alkynes with alkenyl alcohols by using green and low-costing oxygen as the sole oxidant was investigated. This one-pot cascade cyclization proceeds through Pd-catalyzed intramolecular C-O bond cyclization, insertion of nonbiased alkenyl alcohols, β-H elimination, and reinsertion of a HPdX species, which is finally transferred to the target ketones. This method has the advantages of mild conditions, good functional group tolerance, and can be performed with unactivated alkenes to afford isocoumarin derivatives. [ABSTRACT FROM AUTHOR]