Michael addition of α-azido ketones on iminocoumarin derivatives: an efficient access to new functionalized azido chromenes

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

“…Unfortunately, introducing nitro groups in either R 1 or R 2 did not yield the desired products. The structures of the products were confirmed using 1 H-NMR, 13 C-NMR, IR, and HRMS, with the structure of 2 a definitively determined through single-crystal X-ray diffraction (Figure 2). [16] Our proposed mechanism begins with DBN promoting malononitrile to form the malononitrile anion A.…”

“…1 H-NMR Signals were reported relative to Me 4 Si (δ(H) 0.0) or residual CHCl 3 (δ(H) 7.26). 13 C-NMR Signals were reported relative to CDCl 3 (δ(C) 77.16). Multiplicities were described using the following abbreviations: s = singlet, d = doublet, t = triplet, and m = multiplet.…”

“…[12] Later, in 2011, Perumal synthesized these structures using salicylaldehyde derivatives, malononitrile, and 2-azide acetophenone (Scheme 1b). [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 […”

“…J = 5.8 Hz, 2H); 2.24 (s, 3H) 13. C-NMR (101 MHz, CDCl 3 ): 201.4; 160.8; 149.3; 138.3; 137.7; 132.0; 131.5; 128.6; 128.3; 128.2; 125.6; 125.1; 123.4; 119.9; 116.4; 58.7; 50.4; 30.8; 21.2.…”

Synthesis and Consecutive Reactions of α-Azido Ketones: A Review

“…An efficient and simple synthesis of highly functionalized azido chromene derivatives was reported by Babu in 2011 [52]. 2-Aminochromenes are used in many naturally occurring products and in pigments, cosmetics, and agrochemicals.…”