Sequential In-catalyzed intramolecular hydroarylation and Pd-catalyzed cross-coupling reactions using bromopropargyl aryl ethers and amines

Abstract

A sequential one-pot indium-catalyzed intramolecular hydroarylation (IMHA) of bromopropargyl aryl ethers and amines, and palladium-catalyzed cross-coupling reaction using triorganoindium reagents (R 3 In) has been developed. In this transformation, the IMHA of 3-bromo-2-propynyl aryl ethers under indium(III) catalysis, proceeds regioselectively through a 6-endo dig pathway to afford 4-bromo-2H-chromenes. Subsequent palladium-catalyzed cross-coupling with R 3 In gives 4-substituted-2H-chromenes in one-pot. This sequential transformation was extended to 3-bromo-2-propynyl-N-tosylanilines to afford 4-substituted-1,2-dihydroquinolines. The dual-catalyzed procedure takes place efficiently with a variety of propargyl aryl ethers and amines and R 3 In (R = aryl, heteroaryl, alkyl or alkynyl), showing the efficiency of these organometallics and proving the compatibility of indium and palladium in catalysis.

In(III)-TMSBr-Catalyzed Cascade Reaction of Diarylalkynes with Acrylates for the Synthesis of Aryldihydronaphthalene Derivatives

“…On the basis of above experimental results and precedent literature reports [ 38 , 39 , 43 , 44 , 49 ], a plausible reaction pathway for this In(tfacac) 3 -TMSBr-catalyzed cascade reaction of diarylalkynes with acrylates was put forward in Scheme 4 : In(tfacac) 3 and TMSBr would first form a combined Lewis acid complex (LA) with heightened acidity than either of them solely; second, an intramolecular Friedel-Crafts type arylation reaction takes place to generate an alkenyl indium species int-1 ; this is followed by a nucleophilic attack of int-1 onto activated acrylate 2 , giving rise to int-2 , which subsequently attacks another molecule of acrylate to give int-3 ; finally, the int-3 is quenched by the proton generated from the first step to furnish the final product 3 .…”

“…Prominently, the intramolecular hydroarylation of 4-phenyl-1-butyne or its derivatives is one of the most versatile protocols for the construction of aryldihydronaphthalene derivatives [ 12 , 13 , 14 , 15 ]. Since the pioneering studies by Fujiwara et al [ 16 , 17 ], numerous catalytic methods have been developed in this field in which a series of transition metals, Lewis and Bronsted acids have been found effective for catalyzing the hydroarylation [ 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ]. More recently, Corey [ 24 ] and Pérez Sestelo and Martínez [ 38 , 39 ] have independently reported the formation of six-membered oxa- and carbocycles by an In(III)-catalyzed hydroarylation of acetylenic substrates.…”

Iron(III)‐Promoted Synthesis of 3‐(Organoselanyl)‐1,2‐Dihydroquinolines from Diorganyl Diselenides and N‐Arylpropargylamines by Sequential Carbon‐Carbon and Carbon‐Selenium Bond Formation

“…The hydroarylation processes join the carbon nucleophilic of the aryl moiety with more external active carbon of the alkyne in an endo-dig mode (Scheme 1, a). [8] The exo-dig cyclization was also possible giving the fused five-membered heterocycle (Scheme 1, b). [9] In the metal-free hydroarylation reaction, the carbon-carbon bond of alkyne is activated by using an electrophilic source, such as halogen, organoselenium compounds or hypervalent iodine reagent among others, forming a halonium (selenonium) ion intermediate.…”

“…The hydroarylation processes join the carbon nucleophilic of the aryl moiety with more external active carbon of the alkyne in an endo ‐dig mode (Scheme , a) . The exo ‐dig cyclization was also possible giving the fused five‐membered heterocycle (Scheme , b) .…”

Synthesis of 4-Substituted-1,2-Dihydroquinolines by Means of Gold-Catalyzed Intramolecular Hydroarylation Reaction of N-Ethoxycarbonyl-N-Propargylanilines

“…In particular, the synthetic potential of gold catalysis in the IMHA of N -tosyl- N -propargylanilines was explored and the corresponding 4-substituted-1,2-dihydroquinoline derivatives were efficiently isolated ( Scheme 1 a) [ 14 , 15 , 16 ]. Alternatively these latter products can be obtained by the sequential catalyzed IMHA/Pd-catalyzed cross-coupling of 3-bromo-2-propynyl- N -tosylanilines, which afforded the corresponding 4-substituted-1,2-dihydroquinoline derivatives [ 17 , 18 ]. However, the behavior of the substituent attached to N -propargylaniline nitrogen has a significant impact on the reaction outcome.…”