Dual photoredox and nickel-catalyzed desymmetric C–O coupling reactions: visible light-mediated enantioselective synthesis of 1,4-benzodioxanes

Abstract

Chiral 2,2′-bipyridine ligands are key to success in an enantioselective desymmetric C–O cross coupling reaction via dual visible light photoredox and nickel catalysis, resulting in chiral 1,4-benzodioxanes under mild reaction conditions.

Light‐Promoted Nickel Catalysis: Etherification of Aryl Electrophiles with Alcohols Catalyzed by a NiII‐Aryl Complex

“…As in the case of aryl chlorides, the coupling reactions exhibited high efficiency and functional‐group compatibility ( 61 – 79 ). To further demonstrate the application of this new etherification method, intramolecular C−O bond formation was studied ( 80 – 90 ). As shown in Scheme , a series of important five‐ and six‐membered‐ring products were obtained with high yields.…”

Palladium Catalyzed C−O Coupling of Amino Alcohols for the Synthesis of Aryl Ethers

“…Given this historical success (Scheme 1), [4] aryl ether derivatives of amino alcohols continue to emerge from the drug discovery process and practical methodologies that render them readily accessible are sought after in the pharmaceutical industry. [8] While all these methods have different strengths and weaknesses, our highest priority was the expedient development of general and reliable conditions for the scalable production of aryl ethers starting with readily available amino alcohols in support of a swiftly moving drug discovery project. More recently, Ni-promoted coupling reactions, including those utilizing photoredox catalysis, have also been shown to be effective for the synthesis of aryl ethers.…”

“…More recently, Ni-promoted coupling reactions, including those utilizing photoredox catalysis, have also been shown to be effective for the synthesis of aryl ethers. [8] While all these methods have different strengths and weaknesses, our highest priority was the expedient development of general and reliable conditions for the scalable production of aryl ethers starting with readily available amino alcohols in support of a swiftly moving drug discovery project.…”

Light‐Promoted Nickel Catalysis: Etherification of Aryl Electrophiles with Alcohols Catalyzed by a NiII‐Aryl Complex

“…However, owing to the abundance of various electrophiles and alcohols, it would be useful to be able to synthesize such ethers through metal-catalyzed crosscoupling of these two types of starting materials. [5][6][7] Pioneering work based on palladium, [6] copper, [7] and nickel [8] catalysis has been carried out, with the former two metals being most widely used for etherification at the present time. However, all of these C À O coupling reactions necessitate the use of strong inorganic bases or metal alkoxides, which brings solubility and compatibility issues and related operational challenges.…”

“…Recently, two successful strategies for Ni catalyzed C À O couplings of aryl electrophiles with alcohols have in fact been developed. [8] By using a Ni II complex bearing a bulky, electron-rich diphosphine ligand as precatalyst, aryl electrophiles were coupled with alcohols to afford aromatic ethers under thermal conditions (Scheme 1 A). [8a] However, highly basic metal alkoxides were required, which are moisture-sensitive and incompatible with base-sensitive functional groups.…”