This study present a transfer hydrogenation method employing ammonia borane (H 3N·BH 3) as the hydrogen source and inexpensive magnesium as the catalyst for the selective reduction of unprotected indoles, quinoxalines, benzofurans, benzothiophenes, quinolines, and their derivatives, resulting the corresponding alicyclic heterocyclic compounds with desirable yields. This catalytic system is applicable to gram-scale syntheses and demonstrates compatibility with various functional groups, including fluorine, chlorine, bromine, trifluoromethyl, and hydroxyl. Deuterium labeling experiments show that the BH 3 counterpart of NH 3·BH 3 served as the hydride source, while the NH 3 counterpart of ammonia borane acted as a proton source. It offers a novel approach for the preparation of partially saturated heterocyclic derivatives.

Herein, we report an electrochemical multicomponent one-pot cascade protocol for the synthesis of 4-selenylsulfonylpyrazoles from sulfonohydrazides, pentane-2,4-diones and diselenides under catalyst-, chemical oxidant- and electrolyte-free conditions. This method features good functional group tolerance, step economy, mild reaction conditions, environmental friendliness, easy operation with cheap reagents, scaled-up synthesis and high yields, providing a promising strategy to construct pyrazole derivatives containing selenium and sulfonyl, which is widely used in drugs, agricultural chemicals and biologically active compounds. Notably, the representative compound 1-((4-fluorophenyl)sulfonyl)-3,5-dimethyl-4-(phenylselanyl)-1 H-pyrazole 4jaa can inhibit the proliferation of human triple-negative breast cancer cells with an IC 50 value of 5.35 ± 0.76 μM. Moreover, the proposed mechanism is supported by control experiments and density functional theory calculations.

The present work prepared a copper N-heterocyclic carbene complex that could be used in catalyzing the homogeneous hydrogenation of carboxylic acid with ammonia borane (hydrogen source) to synthesize primary alcohols. Various aromatic and aliphatic carboxylic acids with diverse functional groups were transformed to respective alcohols in moderate to high yields. The process can be easily scaled up (TON up to 14545) and exhibit a high compatibility with different sensitive functional groups, including fluorine, chlorine, bromine, iodine, hydroxyl, cyano and nitro groups. IMesCuCl/NH3·BH3 combination can selectively reduce aromatic and aliphatic esters. Mechanistic studies indicate that Cu-H species produced in situ are the active intermediates.

The synthesis of substituted 2-hydroxy-indolin-3-ones has attracted considerable attention of synthetic chemists because they present in numbers of natural products and biologically active molecules. Herein, a novel and convenient copper-catalyzed oxidative intramolecular cyclization of N-(2-acetylphenyl)picolinamide for the synthesis of 2-hydroxy-indolin-3-ones has been developed. Moreover, the detailed mechanism presented is supported by control experiments and density function-al theory calculations. This method provides direct access to 2-hydroxy-indolin-3-ones in high yield and good functional group tolerance. Atom-economy, avoidance of the preparation for substrates and step economy make this protocol be practical. This strategy provides an alternative synthetic method to ex-plore the synthetic application of various types of 2-hydroxy-indolin-3-ones and their enantiopure deriv-atives.

Herein, we present a method for the homogeneous hydrogenation of nitroarenes to produce aromatic amines using low catalyst loading (1 mo%) of air-stable copper N-heterocyclic carbene complexes as the catalyst and ammonia borane as the source of hydrogen. A wide range of nitroarenes, featuring diverse functional groups, were selectively transformed into their corresponding primary aromatic amines with high yields. This process can be readily scaled up and exhibits compatibility with various sensitive functional groups, including halogen, trifluoromethyl, aminomethyl, alkenyl, cyano, ester, amide, and hydroxyl. Notably, this catalytic methodology finds application in the synthesis of essential drug compounds. Mechanistic investigations suggest that the in-situ-generated Cu-H species may serve as active intermediates, with reduction pathways involving species such as azobenzene, 1,2-diphenylhydrazine, nitrosobenzene, and N-phenylhydroxylamine.