Efficient Domino Strategy for the Synthesis of Polyfunctionalized Benzofuran-4(5H)-ones and Cinnoline-4-carboxamides

Abstract

An efficient, three-component strategy for the improved synthesis of multifunctionalized 6,7-dihydrobenzofuran-4(5H)-ones under microwave irradiation in ethyl alcohol within short periods has been established. The synthesized benzofuran-4(5H)-ones have been readily converted into polyfunctionalized cinnoline-4-carboxamides by treating with hydrazine hydratein in the same solvent through a regioselective ring-opening of the furan. Tedious workup procedures can be avoided because of the direct precipitation of products from the reaction solution by water addition, thus rendering the two-steps process ecofriendly.

Synthesis of fused hydroxy dihydropyrroles and unexpected dihydropyrazine and dihydroquinoxaline derivatives based on heterocyclic ketene aminals

“…[14] Pyrazines are useful intermediates for fragrances, pharmaceuticals, and agricultural chemicals that show important biological activities, antimalarial, antiviral, including anti-HIV, anticancer, psychotropic, and aldose reductase inhibitor activities (D, E, and F in Figure 1). [20][21][22][23] To date, many works focus on the development of novel, MCRs, for constructing diverse and highly substituted fused heterocycles from available synthons heterocyclic ketene aminals (HKAs) with advantage for synthetic chemistry. [18] A structure of ring fused with quinoxalines displays diverse pharmacological activities and has found applications in dyes, electron luminescent materials, and chemically controllable switches, as building blocks for the synthesis of anion receptors, cavitands, dehydroannulenes, and organic semiconductors, and as electrontransport materials in multilayer OLEDs.…”

2‐(Alkylamino)‐3‐aryl‐6,7‐dihydrobenzofuran‐4(5H)‐ones: Improved Synthesis and their Photophysical Properties

“…Although many synthetic routes to these compounds can be found in the literature, the previously reported procedures have several disadvantages, such as harsh reaction conditions, limited substrate scope, and poor atom and/or step efficiency . In this context, a Lewis‐acid‐catalyzed [4+1] multicomponent cycloaddition of enones to isocyanides is an important method to synthesize a variety of furans . However, the literature reveals that only a few aryl aldehyde (e.g., 4‐nitrobenzaldehyde and glyoxals) have been investigated for this reaction, with dimedones as the CH acid, to generate 6,7‐dihydrobenzofuran‐4( 5H )‐ones.…”

“…[10][11][12][13][14][15] In this context, aL ewis-acid-catalyzed [4+ +1] multicomponent cycloaddition of enones to isocyanides is an important method to synthesize av ariety of furans. [16][17][18][19][20][21][22] However,t he literature reveals that only af ew aryl aldehyde [19] (e.g.,4 -nitrobenzaldehyde and glyoxals) have been investigated for this reaction, with dimedones as the CH acid, to generate 6,7-dihydrobenzofuran-4(5H)-ones.G iven the limited prior reports,f urther investigation into improving this procedure is warranted.…”

Three-Component Reaction of a 2-Aminoazine, a 2-Oxoaldehyde, and a Cyclic 1,3-Dicarbonyl Compound for the Synthesis of Imidazo[1,2-a]azine Derivatives

“…In their process 6-aminopyrimidines, as exemplified by compound 8 in Scheme d, were used as the urea replacement with the major conceptual difference being the substitution of one N-nucleophilic reactive center with a C-nulceophile. Further, a great number of related multicomponent processes have been discovered and documented . In a continuation of our ongoing efforts in the development of Biginelli-type transformations and methods for the assembly of fused imidazoles we were interested in exploring this chemistry with 2-aminoazines 10 which, like ureas 1a and 1b , have two N-nucleophilic centers.…”