Ni-Catalyzed electrophile driven regioselective arylative cyclization of ortho-functional diaryl acetylenes for the synthesis of pyridine and indene derivatives

Abstract

A regioselective arylative cyclization of ortho functional diaryl acetylenes for the synthesis of selectively substituted diaryl pyridine and indene derivatives is accomplished through an electrophile driven alkyne polarization.

Enantioselective Nickel‐Catalyzed anti‐Arylmetallative Cyclizations onto Acyclic Ketones

“…However, acyclic ketones are potentially less reactive than cyclic 1,3‐diketones because of their greater conformational flexibility, and because they lack the activation from the second ketone through its electron‐withdrawing effect as well as the electronic repulsion caused by having aligned dipoles. Two individual examples of non‐asymmetric nickel‐catalyzed arylative cyclizations onto acyclic ketones have been reported recently, [6d] but to our knowledge, corresponding enantioselective processes have yet to be described.…”

Nickel‐Catalyzed Arylative Cyclizations of Alkyne‐ and Allene‐Tethered Electrophiles using Arylboron Reagents

“…[90] The first of these is anti-arylmetallative cyclization. [17,18,[61][62][63][64][65][66][67][68][69][70] Here, the reactions are initiated by transmetalation of the arylboronic acid with the nickel complex 8 (formed by coordination of a ligand to a nickel(II) salt) to give arylnickel species 9 (Scheme 2A). Coordination of 9 to the alkyne of the substrate 1, followed by syn-stereospecific migratory insertion of the alkyne places nickel distal to the electrophile.…”

“…More recently, nickel catalysis has also been shown to be highly effective in these reactions. [61][62][63][64][65][66][67][68][69][70][71][72][73][74][75] As well as being less expensive and more readily available than the more commonly used rhodium or palladium catalysts, nickel catalysis can offer unique possibilities in reaction development not readily available to these other catalyst systems. [76][77][78][79][80][81][82][83][84][85][86][87][88][89] This review will describe nickel-catalyzed arylative cyclizations of alkyne-and allene-tethered electrophiles using arylboron reagents, that proceed by the general mechanistic pathways shown in Scheme 1.…”

Enantioselective nickel-catalyzed arylative and alkenylative intramolecular 1,2-allylations of tethered allene–ketones

“…On the basis of our recent work in nickel-catalyzed arylative cyclizations involving allenes as substrates ( Schemes 1A and 1B ), 8 it occurred to us that chiral pyrrolidin-2-ones with a C3 tertiary alcohol might be prepared by the nickel-catalyzed reaction of tethered allene– α-ketoamides 1 with arylboronic acids ( Scheme 1C ). 9,10 Nickel-catalyzed addition of an arylboronic acid to the allene would give an intermediate allylnickel species, 8 which could exist as several interconverting σ- and π-allyl isomers (representative structures A and A′ are shown), which could then engage in enantio- and diastereoselective nucleophilic allylation 11 of the ketone to give pyrrolidin-2-one 2 . 12–14 While enantioselective metal-catalyzed nucleophilic allylations of carbonyl compounds are well-known, 15 the closest approach to that shown in Scheme 1C is work described by groups of Tsukamoto 16 a and Lu 16 b to give other types of hetero- and carbocycles.…”

“…With L3 as the ligand, changing the mixed solvent system to MeCN or 1,4-dioxane alone offered noimprovement (entries 6 and 7). Finally, we tested TFE (2,2,2-trifluoroethanol) as the solvent, 9 b , c which gave 2a in almost quantitative yield after filtration of the crude reaction mixture through plug of a silica gel, with only a slight decrease in enantioselectivity (entry 8). On the basis of these results, the conditions of entry 8 were selected for subsequent experiments.…”