Copper-Catalyzed [5 + 1] Annulation of 2-Ethynylanilines with an <i>N</i>,<i>O</i>-Acetal Leading to Construction of Quinoline Derivatives

A novel copper-catalyzed [5 + 1] annulation of 2-ethynylanilines with an <i>N</i>,<i>O</i>-acetal, which functioned as a C1 part, leading to the preparation of quinoline derivatives with an ester substituent on the 2-position is described. A combination of CuBr₂ and trifluoroacetic acid (TFA) promoting [5 + 1] annulation of the 2-ethynylaniline with ethyl glyoxylate is also demonstrated

Gallium-Catalyzed Reductive Chlorination of Carboxylic Acids with Copper(II) Chloride

Described herein is the direct chlorination of carboxylic acids using copper­(II) chloride via a gallium­(III)-catalyzed reduction in the presence of a hydrosiloxane. During this reductive chlorination, the counteranions of CuCl₂ functioned as a chloride source

Indium-Catalyzed Reductive Bromination of Carboxylic Acids Leading to Alkyl Bromides

The combination of 1,1,3,3-tetramethyldisiloxane (TMDS) and trimethylbromosilane (Me₃SiBr) with a catalytic amount of indium bromide (InBr₃) undertook direct bromination of carboxylic acids, which produced the corresponding alkyl bromides in good to excellent yields. The reducing system was tolerant to several functional groups

Indium(III)-Catalyzed Reductive Bromination and Iodination of Carboxylic Acids to Alkyl Bromides and Iodides: Scope, Mechanism, and One-Pot Transformation to Alkyl Halides and Amine Derivatives

Highly effective indium­(III)-catalyzed reductive bromination or iodination of a variety of carboxylic acids with 1,1,3,3-tetramethyldisiloxane (TMDS) and a source of bromine or iodine is described. This functional group interconversion has high tolerance for several functional groups, such as halogens, a hydroxy group, a nitro group, an olefin part, and a sulfide moiety. This indium catalytic system is also applicable to the reductive iodination of aldehyded, acyl chlorides, and esters. Furthermore, this reducing system can be applied to the one-pot synthesis of alkyl halides and amine derivatives via the addition of nucleophiles. Insight into the reaction mechanism was gained via the time course of ¹H and ¹³C NMR monitoring experiments and the corresponding stepwise reactions

Single-Step Thioetherification by Indium-Catalyzed Reductive Coupling of Carboxylic Acids with Thiols

Direct thioetherification from a variety of aromatic carboxylic acids and thiols using a reducing system combined with InBr₃ and 1,1,3,3-teramethyldisiloxane (TMDS) in a one-pot procedure is demonstrated. It was also found that a system combined with InI₃ and TMDS underwent thioetherification of aliphatic carboxylic acids with thiols