Selective Synthesis of Cyano-Functionalized 2-Aryl-4H-chromenes and 2-Amino-4H-chromene-3-carbonitriles by Catalyst-Tuned Reactions of 2-Hydroxychalcones with 2-Substituted Acetonitriles

Abstract

A selective synthesis of 4H-chromenes by the reactions of 2-hydroxychalcone derivatives with acetonitriles substituted with electron-withdrawing groups is described. Under catalyst-free conditions, the reactions give cyano-functionalized 2-aryl-4H-chromenes, whereas in the presence of sodium bicarbonate, 2-amino-4H-chromene-3-carbonitriles are obtained in excellent yields.

One-pot synthesis of 4-alkyl-2-amino-4H-chromene derivatives

“…The first involves the reaction of 2-(2-acyl-or 2-nitrovinyl) phenols and malononitrile that leads to the 4-acyl-or 4-nitromethyl-2-amino-4H-chromenes [15][16][17]. The second variant is based on the base-initiated reaction between 3,4-unsubstituted coumarins and malononitrile followed by ring-opening and ring-closing reactions [13,14,18].…”

Advancements in the Preparation of 4H‐Chromenes: An Overview

“…Compared to those reports, Yin et al . in 2013 employed 2‐substituted acetonitriles 155 as nucleophiles, and achieved a catalyst‐free selective synthesis of cyano‐functionalized 2‐aryl‐4 H ‐chromenes 156 from 2‐hydroxychalcones 67 [38] . All tested substrates underwent this tandem reaction to give the desired products 156 in 79–90% yields within 6–12 h (Scheme 40).…”

“…[4c] Compared to those reports, Yin et al in 2013 employed 2-substituted acetonitriles 155 as nucleophiles, and achieved a catalyst-free selective synthesis of cyano-functionalized 2-aryl-4H-chromenes 156 from 2-hydroxychalcones 67. [38] All tested substrates underwent this tandem reaction to give the desired products 156 in 79-90% yields within 6-12 h (Scheme 40). Interestingly, the introduction of NaH-CO 3 as base and using EtOH as solvent allowed the formation of 2-amino-4H-chromenes 157 in high yields.…”

DBN Promoted [4+2] Annulation of Malononitrile and 2‐(3‐Oxo‐3‐arylprop‐1‐en‐1‐yl)phenyl buta‐2,3‐dienoates to Construct 2‐Amino‐4‐(2‐oxo‐2‐phenylethyl)‐4H‐chromene‐3‐carbonitriles

“…[13] Tao in 2012 incidentally synthesized this structure as a byproduct while aiming for the 2-(4H-chromen-4-yl)malononitrile structure (Scheme 1c). [14] Motivated by these studies, we introduce a novel DBN-promoted […”