B(C6F5)3-Catalyzed Highly Chemoselective Reduction of Isatins: Synthesis of Indolin-3-ones and Indolines

Oxidative Transformation of 2-Furylanilines into Indolin-3-ones

Oxidation of 2-furylaninlies with m-CPBA followed by treatment with a base provides access to functionalized indolin-3-ones. The designed oxidative transformation utilizes an underassessed chemical behavior of furyl-containing amines to form a C-N bond via engaging a β-carbon atom of the furan core upon a ring-forming step, thereby providing an alternative disconnection toward nitrogen-containing heterocycles.

Modified Chemoselective Reduction and Consecutive Regioselective Deuteration Reaction Catalyzed by B(C6F5)3

An efficient chemoselective reduction of isatin derivatives using catalyst B(C₆F₅)₃, benzyldimethylsilane, and H₂O is described. Notably, a small amount of water is shown to be a highly effective reaction promoter that decreases the reaction time and temperature for the synthesis of indolin-3-ones. Moreover, using method, excellent deuterium incorporation is achieved via the catalytic α-deuteration of indolin-3-ones using B(C₆F₅)₃ and D₂O.

Nickel-catalyzed remote hydrosilylation of unconjugated enones with bulky triphenylsilane

Herein we describe a nickel-catalyzed remote hydrosilylation of unconjugated enones with bulky triphenylsilane. A range of Z-silyl enol ethers are obtained as major isomers due to the process of nickel triggered alkene isomerization. Notably, some specific alkyl silyl enol ethers can be prepared from this protocol, which are not easily accessed by the traditional strategy using a strong base and chlorosilane. This reaction features 100% atom economy, simple reaction conditions, and good yields.

Tris(pentafluorophenyl)borane catalyzed C-C and C-heteroatom bond formation

A series of boron based Lewis acids have been reported to date, but among them, tris(pentafluorophenyl)borane (BCF) has gained the most significant attention in the synthetic chemistry community. The viability of BCF as a potential Lewis acid catalyst has been vastly explored in organic and materials chemistry due to its thermal stability and commercial availability. Most explorations of BCF chemistry in organic synthesis has occurred in the last two decades and many new catalytic reactivities are currently under investigation. This review mainly focuses on recent reports from 2018 onwards and provides a concise knowledge to the readers about the role of BCF in metal-free catalysis. The review has mainly been categorized by different types of organic transformation mediated through BCF catalysis for the C-C and C-heteroatom bond formation.