Palladium(II) Chloride‐Catalyzed Aerobic Oxidative Intermolecular Cycloaddition Reaction of 2‐Alkynylbenz‐ aldehydes and Electron‐Deficient Terminal Alkenes: An Efficient Synthesis of Naphthyl Ketones

Abstract

We describe a simple and efficient synthetic methodology for the synthesis of a library of 2,4dicarbonyl-substituted naphthalene derivatives through the PdCl 2 -catalyzed aerobic oxidative intermolecular cycloaddition of 2-alkynylbenzaldehydes to some electron-deficient terminal alkenes. A wide variety of functionalized 2-alkynylbenzaldehydes and electron-deficient alkenes were examined for this reaction to deliver the corresponding naphthyldicarbonyl compounds in moderate to good yields.

One-Pot Dual C–C Bond-Forming Cascade Process via Suzuki Coupling and Intramolecular Cyclocondensation: An Access to Functionalized Naphthalenes

“…In 2014, the research group of Balamurugan developed a protocol to access functionalized naphthyl ketones through the incorporation of acetal and alkyne-carbonyl metathesis/annulation of ortho-alkynylacetophenone . Yao and group reported dicarbonyl-substituted naphthalene derivatives through the PdCl 2 -catalyzed aerobic oxidative intermolecular cycloaddition of 2-alkynylbenzaldehydes to some electron-deficient terminal alkenes (Scheme d) . Wu and group demonstrated the direct ring construction of amides with alkynes catalyzed by PdCl 2 with an oxidant (Scheme a) .…”

“…27 Yao and group reported dicarbonyl-substituted naphthalene derivatives through the PdCl 2 -catalyzed aerobic oxidative intermolecular cycloaddition of 2-alkynylbenzaldehydes to some electrondeficient terminal alkenes (Scheme 1d). 28 Wu and group demonstrated the direct ring construction of amides with alkynes catalyzed by PdCl 2 with an oxidant (Scheme 1a). 29 Feng and Loh also reported palladium-mediated bisolefination of C−C triple bond with olefin using oxygen for naphthalene synthesis (Scheme 1b).…”

Gold(I) or Gold(III) as Real Intermediate Species in Gold-Catalyzed Cycloaddition Reactions of Enynal/Enynone?

“…Among enynals and enynones, o -alkynylbenzaldehydes (enynals) and o -alkynylarylketones (enynones) are the most powerful, general, and widely used, showing great versatility and high reactivity toward cyclization reactions. Under activation of a transition metal catalyst, such as Au, − Ag, Cu, Pd, In, Pt, Re, Zn, or W, o -alkynylbenzaldehydes and o -alkynylarylketones ( 1 ) could undergo cyclization to afford intriguing isobenzopyrylium intermediates A in the first place (Scheme a), which can further react with a range of reaction partners to construct various polycyclic compounds through [4 + 2] or [3 + 2] cycloaddition pathways . Both gold­(I) and gold­(III) have been employed as efficient catalysts toward these reactions.…”

N-Arylation of Amino Acid Esters via an I2-Mediated Metal-Free Multicomponent Benzannulation Strategy

“…Meanwhile, the construction of benzene skeletons has received a great deal of attention from synthetic chemists since substituted benzene frameworks are present in numerous natural products and pharmaceuticals, which are of immense biological importance. − Traditional synthetic strategies to access substituted benzene are mainly based on Diels–Alder reactions of common dienophiles with dienes involving furans. , The dominant methods are transition-metal-catalyzed benzannulation of alkynes or alkenes to construct the functionalized benzenes. − Recent work has enabled benzene skeleton construction to be performed with a growing number of simple acyclic precursors, such as electron-deficient olefins, α,β-unsaturated ketones, chlorocyclopropane, and active methylene compounds . In addition, some convergent reaction strategies were also used to construct the aryl framework, such as tandem reactions and organocatalytic benzannulation reactions. − On the other hand, amino acids are derived from renewable resources, and their racemic or natural forms are cheap and readily available in varieties.…”