A straightforward copper-free palladium methodology for the selective alkynylation of a wide variety of S-, O-, and N-based mono- and diheterocyclic bromides and chlorides

Expanding the Scope of Arylsulfonylacetylenes as Alkynylating Reagents and Mechanistic Insights in the Formation of Csp2Csp and Csp3Csp Bonds from Organolithiums

“…Reaction of electron-poor aryllithium 2 G with 1 h is similarly successful (entry 11, Table 2), revealing that the electronic properties of the rings taking part in the organolithium or in the arylacetylene are not essential to the reaction. Finally, the alkynylation of pyridines [22,23] can be also performed from 2-halo pyridines by lithium-A C H T U N G T R E N N U N G halogen exchange followed by reaction with a sulfonylacety-A C H T U N G T R E N N U N G lene. We have illustrated this fact with the preparation of 4 aH and 4 bH from 2-bromopyridine (entries 12 and 13, Table 2).…”

Highly Dispersed Palladium–Polypyrrole Nanocomposites: In‐Water Synthesis and Application for Catalytic Arylation of Heteroaromatics by Direct C–H Bond Activation

“…We investigated the coupling of furan and thiophene heteroaromatics with activated and unactivated bromoarenes. Aryl bromides are significantly more challenging coupling partners than iodoarene substrates, which are classically used with catalytic materials,11b but are more widely available and much less costly 30…”

A Versatile and Efficient Palladium–meta‐Terarylphosphine Catalyst for the Copper‐Free Sonogashira Coupling of (Hetero‐)Aryl Chlorides and Alkynes

“…Over the past several decades, remarkable achievements have been made in the development of homogeneous Pd catalysts for the Sonogashira transformation in both the in situ and precatalyst form 6. However, until only recently, no general and practical protocols applicable to heteroaromatic alkynylation were available 7. As convenient methods are highly sought after, the use of ordinary palladium–phosphine catalyst combinations {i.e., [Pd(allyl)Cl] 2 /PPh 3 } in ionic liquids has taken a progressive step towards the practical coupling of heteroaromatic bromides with simple alkynes in the absence of Cu co‐catalysts 7,8.…”

“…However, until only recently, no general and practical protocols applicable to heteroaromatic alkynylation were available 7. As convenient methods are highly sought after, the use of ordinary palladium–phosphine catalyst combinations {i.e., [Pd(allyl)Cl] 2 /PPh 3 } in ionic liquids has taken a progressive step towards the practical coupling of heteroaromatic bromides with simple alkynes in the absence of Cu co‐catalysts 7,8. However, for general applicability using less reactive aryl chloride substrates, several standout examples employing copper‐free conditions have been reported by Buchwald,9a,10a Beller,9b Hua,10b,10c Colacot,10d–10f and Plenio 9i…”

“…[7] As convenient methods are highly sought after, the use of ordinary palladium-phosphine catalyst combinations {i.e., [Pd(allyl)Cl] 2 /PPh 3 } in ionic liquids has taken a progressive step towards the practical coupling of heteroaromatic bromides with simple alkynes in the absence of Cu co-catalysts. [7,8] However, for general applicability using less reactive aryl chloride substrates, several standout 7184 dustry by featuring a diverse range of challenging, electronrich aryl chlorides and terminal alkynes. The Pd-Cy*Phine catalyst was able to deliver products in excellent yields with efficient substrate utilization, which minimizes the generation of commonly formed byproducts, and the reaction is tolerant of a variety of substrates with unprotected functional groups.…”