A Dual Palladium and Copper Hydride Catalyzed Approach for Alkyl–Aryl Cross‐Coupling of Aryl Halides and Olefins

Abstract

We report an efficient means of sp –sp cross coupling for a variety of terminal monosubstituted olefins with aryl electrophiles using Pd and CuH catalysis. In addition to its applicability to a range of aryl bromide substrates, this process was also suitable for electron-deficient aryl chlorides, furnishing higher yields than the corresponding aryl bromides in these cases. The optimized protocol does not require the use of a glovebox and employs air-stable Cu and Pd complexes as precatalysts. A reaction on 10 mmol scale further highlighted the practical utility of this protocol. Employing a similar protocol, a series of cyclic alkenes were also examined. Cyclopentene was shown to undergo efficient coupling under these conditions. Lastly, deuterium-labeling studies indicate that deuterium scrambling does not take place in this sp2–sp3 cross coupling, implying that β-hydride elimination is not a significant process in this transformation.

Complexes between cyclopentene and cyclopentyne derivatives with HCu and FCu: The importance of cyclization effects

“…In this respect, it should be emphasized that CuH also catalyze the reduction of carbonyl groups and CuH nanoclusters exhibit unique selectivity for the electrocatalytic CO 2 reduction and this selectivity can only be understood through the use of adequate theoretical models . Also, Pd and CuH catalyze cross‐coupling of aryl halides and olefins . A very interesting and complete review of the catalytic properties of coinage metal hydrides was recently published …”

Phosphite‐Catalyzed C−H Allylation of Azaarenes via an Enantioselective [2,3]‐Aza‐Wittig Rearrangement

“…We report herein the first enantioselective CÀHallylation of azaarenes via ac onceptually novel chiral phosphitepromoted [2,3]-aza-Wittig rearrangement ( Figure 1c). Our interest in enantioselective CÀHf unctionalization of imines embedded in azaarenes prompted us to explore the possibility of umpolung reactivity.…”

“…Abstract: Ap hosphite-mediated [2,3]-aza-Wittig rearrangement has been developed for the regio-and enantioselective allylic alkylation of six-membered heteroaromatic compounds (azaarenes). The nucleophilic phosphite adducts of N-allyl salts undergo as tereoselective base-mediated aza-Wittig rearrangement and dissociation of the chiral phosphite for overall C À Hf unctionalization of azaarenes.T his method provides efficient access to tertiary and quaternary chiral centers in isoquinoline,q uinoline,a nd pyridine systems,t olerating ab road variety of substituents on both the allyl part and azaarenes.C atalysis with chiral phosphites is also demonstrated with synthetically useful yields and enantioselectivities.…”

“…[2] Fore xample,m ethods have been developed that commence from acyclicp recursors or prefunctionalized azaarene halides and organometallic reagents. [2,3] Recently, elegant protocols for the direct CÀHa lkylation from feedstock azaarenes have also been reported. [4][5][6] Unfortunately, an enantioselective CÀHallylation of azaarenes has remained elusive,d espite the potential utility of the synthetically versatile chiral allylated azaarene products for further functionalization (Figure 1b).…”

“…Thelower enantioselection for most of the quinoline and pyridine substrates prompted us to look into the possible effect of alkene geometry.U nlike [3,3]-rearrangements that proceed through well-ordered six-membered transition states, the stereoselectivity of [2,3]-rearrangements is often less predictable and influenced by the nature and size of substituents,p resumably because of the conformationally more flexible five-membered transition states. [12a, 15, 16] Hence, we synthesized cis-allyl salts of quinoline (cis-1t), isoquino- …”