K2CO3-promoted synthesis of amides from 1-aryl-2,2,2-trifluoroethanones and amines under mild conditions.

A base-promoted amidation of 1-aryl-2,2,2-trifluoroethanones with amines via Haller-Bauer reaction has been developed. In this reaction, the direct transformation of 1-aryl-2,2,2-trifluoroethanones into amides via C(O)-C bond cleavage occurs without the use of any stoichiometric chemical oxidants or transition-metal catalysts. A series of primary and secondary amines are shown to be compatible with this transformation, and several pharmaceutical molecules were synthesized.

Cyclometalated iridium complexes-catalyzed acceptorless dehydrogenative coupling reaction: construction of quinoline derivatives and evaluation of their antimicrobial activities.

The acceptorless dehydrogenative coupling (ADC) reaction is an efficient method for synthesizing quinoline and its derivatives. In this paper, various substituted quinolines were synthesized from 2-aminobenzyl alcohols and aryl/heteroaryl/alkyl secondary alcohols in one pot via a cyclometalated iridium-catalyzed ADC reaction. This method has some advantages, such as easy availability of raw materials, mild reaction conditions, wide range of substrates, and environmental friendliness which conforms to the principles of green chemistry. Furthermore, a gram-scale experiment with low catalyst loading offers the potential to access the aryl/heteroaryl quinolones in suitable amounts. In addition, the antibacterial and antifungal activities of the synthesized quinolines were evaluated in vitro, and the experimental results showed that the antibacterial activities of compounds 3ab, 3ad, and 3ah against Gram-positive bacteria and compound 3ck against C. albicans were better than the reference drug norfloxacin.

Facile access to the 2,2-difluoro-2,3-dihydrofuran skeleton without extra additives: DMF-promoted difluorocarbene formation of ClCF2CO2Na.

A practical and facile difluorocarbene-triggered cycloaddition reaction of enaminones was developed, which delivered 2,2-difluoro-2,3-dihydrofurans with a broad substrate scope. Notably, the reaction proceeded smoothly without any extra additives. Readily available sodium chlorodifluoroacetate (ClCF2CO2Na, SCDA) served as a difluorocarbene precursor in this transformation through DMF-promotion. Moreover, it is proved that the 2,2-difluoro-2,3-dihydrofuran derivatives exhibit potential antiproliferative activity against human tumour cells HeLa, MCF7 and HepG2.

Nickel-Catalyzed Reductive Borylation of Enaminones via C(sp2)-N Bond Cleavage.

The cleavage and transformation of alkenyl C(sp2)-N bonds is a significant synthetic challenge. Herein we described an unprecedented nickel-catalyzed reductive borylation of enaminones to synthesize ß-ketone boronic esters. Notably, B2pin2 played the dual role in this process, and water served as a hydrogen source, which was transferred to target products. The air-stable nickel catalyst was applied to the cleavage of alkenyl C(sp2)-N bonds, concomitant with the reductive process of the alkenyl boronic ester intermediates, on the basis of the mechanism study.

Two new phenolic glucosides from marine-derived fungus Aspergillus sp.

Two new phenolic glucosides, including a new O-glycoside (1) and a new C-glycoside (2), were isolated from a marine-derived fungus Aspergillus sp. The structures of new compounds were elucidated through interpretations of spectroscopic evidence and high-resolution electrospray ionization mass spectrometry. The hexose unit of 1 was identified as ß-D-glucose by comparison with an authentic sample via HPLC after acid hydrolysis and derivatization. All compounds were evaluated for their ability to inhibit LPS-induced NO production in RAW264.7 macrophages, but none of them displayed significant activity.

pH-Mediated Selective Synthesis of N-Allylic Alkylation or N-Alkylation Amines with Allylic Alcohols via an Iridium Catalyst in Water.

Amination of allylic alcohols is an effective approach in the facile synthesis of N-allylic alkylation or N-alkylation amines. Recently, a series of catalysts were devised to push forward this transformation. However, current synthetic methods are typically limited to achieve either N-allylic alkylation or N-alkylation products via a certain catalyst. In this article, a pH-mediated selective synthesis of N-allylic alkylation or N-alkylation amines with allylic alcohols via an iridium catalyst with water as the environmental benign solvent is revealed, enabling the miscellaneous synthesis of N-allylic alkylation and N-alkylation products in outstanding yields. Furthermore, a gram-scale experiment with low catalyst loading offers the potential to access a distinct entry for the synthesis of the antifungal drug naftifine.

Substrate-Controlled Cu(OAc)2-Catalyzed Stereoselective Semi-Reduction of Alkynes with MeOH as the Hydrogen Source.

A substrate-controlled stereoselective semi-reduction of alkynes with MeOH as the hydrogen source has been developed, and readily available Cu(OAc)2 (copper acetate) is utilized as an optimal catalyst. The detailed investigation of the mechanism revealed distinct catalytic processes for the (Z)- and (E)-alkenes, respectively. As a result, a diversity of alkynes (including terminal, internal alkynes etc.) were compatible under the mild reaction conditions. Furthermore, the high proportion of deuterium in Z-alkenes (up to 96%) was obtained using d 4-methanol as a solvent.

Amide Iridium Complexes As Catalysts for Transfer Hydrogenation Reduction of N-sulfonylimine.

Sulfonamide moieties widely exist in natural products, biologically active substance, and pharmaceuticals. Here, an efficient water-soluble amide iridium complexes-catalyzed transfer hydrogenation reduction of N-sulfonylimine is developed, which can be carried out under environmentally friendly conditions, affording a series of sulfonamide compounds in excellent yields (96-98%). In comparison with organic solvents, water is shown to be critical for a high catalytic transfer hydrogenation reduction in which the catalyst loading can be as low as 0.001 mol %. These amide iridium complexes are easy to synthesize, one structure of which was determined by single-crystal X-ray diffraction. This protocol gives an operationally simple, practical, and environmentally friendly strategy for synthesis of sulfonamide compounds.

Cyclometalated Iridium Complex-Catalyzed N-Alkylation of Amines with Alcohols via Borrowing Hydrogen in Aqueous Media.

This paper develops a methodology for cyclometalated iridium complex-catalyzed N-alkylation of amines with alcohols via borrowing hydrogen in the aqueous phase. The cyclometalated iridium catalyst-mediated N-alkylation of amines with alcohols displays high activity (S/C up to 10,000 and yield up to 96%) and ratio of amine/imine (up to >99:1) in a broad range of substrates (up to 46 examples) using water as the green and eco-friendly solvent. Most importantly, this transformation is simple, efficient, and can be performed at a gram scale, showcasing its potential for industrially synthesizing N-alkylamine compounds.