Pt^IV‐Catalyzed Cyclization of Arene—Alkyne Substrates via Intramolecular Electrophilic Hydroarylation.

Abstract

Benzopyran derivatives Benzopyran derivatives R 0350Pt IV -Catalyzed Cyclization of Arene-Alkyne Substrates via Intramolecular Electrophilic Hydroarylation. -PtCl 4 is shown to be an effective catalyst for the intramolecular hydroarylation tolerating diverse structural features including propargyl ethers, propargylamines and alkynoate esters. -(PASTINE, S.

Computational Study on Cycloisomerization/Oxidative Dimerization of Aryl Propargyl Ethers Catalyzed by Gold Nanoclusters: Mechanism and Selectivity

“…Intramolecular hydroarylation of alkynes catalyzed by transition metal complexes through the addition of an aryl C–H bond across a π-bond has attracted considerable attention because it is a valuable synthetic alternative to the Heck and cross-coupling processes for the synthesis of alkenyl arenes. − Since Pd(II)-catalyzed intramolecular hydroarylation of alkynes (Scheme ) was first reported by Fujiwara and co-workers, , a wide range of transition metal-, Lewis acid- (e.g., GaCl 3 , InCl 3 ), and Brønsted acid-catalyzed intramolecular hydroarylation of alkyne reactions have been reported. The intramolecular hydroarylation of alkynes catalyzed by transition metal complexes such as Ru(II), Pt(II), , Hg(II), and PtCl 4 to give dihydronaphthalene and naphthalene derivatives (Scheme ), PtCl 2 -catalyzed reaction producing phenanthrenes (Scheme ), Pd(II)-, ,,, PtCl 4 -, and Fe(III)-catalyzed cyclization of arene-alkynes to 2 H -chromene and dihydroquinoline derivatives (Scheme ), and Pd(II)-mediated fluorene synthesis via the palladium-catalyzed 5-exo - dig annulation of o -alkynylbiaryls (Scheme ) − have been intensively studied. Lewis acids, such as GaCl 3 and InCl 3 , and the Brønsted acid HNTf 2 have been used to catalyze the cyclization of arene-alkynes (Scheme ). − Gold(I) complexes are active for the intramolecular hydroarylation of terminal alkynes to synthesize coumarins, benzofurans, and dihydroquinolines (Scheme ). , Au(III) catalyzes the domino cyclization and oxidative coupling of phenyl propiolate (Scheme ). , Recently, the heterogeneous gold-based catalyst Au/TiO 2 has been found to activate C–C triple bonds and effectively catalyze the selective cycloisomerization of aryl propargyl ethers to the corresponding 2 H -chromenes by Stratakis et al 2 H ,2′ H -3,3′-Bichromenes resulting from a catalytic oxidative dimerization pathway are also formed as byproducts (Scheme ) …”