Brønsted Acid-Promoted One-Pot Synthesis of Chrysene Derivatives via Isochromenylium Intermediate Formed in Situ

Abstract

Trifluoromethanesulfonic acid (HOTf) promoted cross-coupling of ortho-[2-(4-methoxylphenyl)-alkynyl]acetophenones with ortho-alkynylbenzaldehydes affording chrysene derivatives has been developed. The present cascade reaction provides a facile one-pot synthesis of multisubstituted chrysenes as well as naked chrysene under mild conditions. The mechanism experimental results demonstrate isochromenylium is a key intermediate for this transformation.

Isoquinolone Synthesis via Zn(OTf)2-Catalyzed Aerobic Cyclocondensation of 2-(1-Alkynyl)-benzaldehydes with Arylamines

“…Encouraged by the results obtained above, we studied the substrate scope for the formation of isoquinolin-1(2H)-ones using various ortho-alkynylbenzaldehydes and amines bearing different substituents under the conditions of entry 6 in Table 1. As can be seen from Table 2, βaminonaphthalene (2b), para-substituted anilines (para-Me, 2c; parai Pr, 2d; para-Br, 2f), 2-methyl-3methoxyaniline (3e), and 2,4-difluoroaniline (2g) underwent cyclocondensation with 1a affording the Recently, we have been interested in the applications of 2-(1-alkynyl)benzaldehydes in the synthesis of benzo-fused cyclic compounds [28,33,39], air-stable Lewis acids as catalysts in organic transformation [40][41][42][43][44], and the development of synthetic methods for the formation of nitrogen-heterocyclic compounds via alkyne annulations [45][46][47][48][49][50][51][52][53]. Therefore, in continuation of our interests in the application of 2-(1-alkynyl)benzaldehydes, we herein describe a simple and efficient method for the construction of isoquinolone from the cyclocondensation of 2-(1-alkynyl)benzaldehydes with arylamines in the presence of a catalytic amount of Zn(OTf) 2 (Scheme 1, eq.…”

“…All commercial organic/inorganic reagents and solvents were analytically pure and used without further purification; 2-(1-alkynyl)benzaldehydes (1a-f) are known compounds and were prepared by cross-coupling reactions of 2-bromobenzaldehydes with terminal aryl acetylenes [39]. Nuclear magnetic resonance (NMR) spectra were recorded on a JEOL ECA-400 spectrometer (JEOL, Tokyo, Japan) using CDCl 3 as solvent at 298 K. The 1 H NMR (400 MHz) chemical shifts (δ) were referenced to internal standard TMS (for 1 H, δ = 0.00); 13 C NMR (100 MHz) chemical shifts were referenced to internal solvent CDCl 3 (for 13 C, δ = 77.16).…”

“…Among the different protocols for achieving this goal, the synthetic strategies starting from 2-(1-alkynyl)benzaldehydes are the most interesting due to their high atom utilization [15,21] (Scheme 1). Although the readily available 2-(1-alkynyl)benzaldehydes have been well-applied in the synthesis of benzo-fused six-membered heterocycles [27][28][29][30][31][32][33] and carbocycles [34][35][36][37][38][39], their applications for isoquinolone synthesis are very rare. As shown in Scheme 1, only two procedures have been reported to approach isoquinolones from the direct intermolecular cyclocondensation of 2-(1-alkynyl)-benzaldehydes with primary amines.…”

Isoquinolone Syntheses by Annulation Protocols

“…Readily available ortho-(1-alkynyl)benzaldehydes have been well-applied in the synthesis of benzo-fused heterocycles [85][86][87][88][89][90][91] and carbocycles [92][93][94][95][96][97], which are also used as C5 synthon in the syntheses of isoquinolones by the intermolecular [5 + 1] cyclocondensation with primary amines.…”

Palladium-Catalyzed Copper-Free Sonogashira Coupling of 2-Bromoarylcarbonyls: Synthesis of Isobenzofurans via One-Pot Reductive Cyclization

“…2-Alkynylaryl carbonyl compounds are indispensable synthons for the synthesis of various carbocyclic and heterocyclic compounds of natural and unnatural interest. Some of the notable examples include the preparation of indenones, 1 polycyclic indoles, 2 fused pyrrole systems, 3 3benzazepines, 4 fused pyrazoles, 5 trifluoromethylated phthalans, 6 isochromenes, 7 isoquinolines, 8 oxazolo-fused pyrroloquinolines, 9 naphthalenes, 10 chrysene derivatives, 11 fluorenes, 12 benzothiophenes, 13 triazolo-heterocyclics, 14 spiro systems, 15 and complex bridged molecules. 16 Consequently, there were reports on the synthesis of 2-alkynylaryl carbonyls via Sonogashira coupling.…”