One-pot synthesis of 2-alkyl/arylamino-4-oxo-4H-1-benzopyran-3-carboxaldehyde from 4-oxo-4H-1-benzopyran-3-carboxaldehyde

Abstract

Zn/NH 4 Cl -Mediated reactions of aldehyde 1 with nitro compounds 2 afford 2-(Nalkyl/arylamino)-3-formylchromones 4, which on heating with 70% H 2 SO 4 produces 9a-d and 11e-h from 4a-d and 4e-h, respectively. The synthesis of the aminochromone class of compounds has received considerable attention because of the wide range of biological activities. 5, 4'-Diaminoflavone and some of its congeners exhibited a remarkable antiproliferative effect against the human breast cancer cell line MCF -7 irrespective of the presence or absence of estrogen. 1 Increasing interest in the 2-aminochromone class of compounds is due to the antiplatelet activity. 2 2-(N, N-Dialkylamino)chromone has been synthesised (i) by reacting salicylic esters with ynamines, 2a (ii) by Vilsmeier condensation of β-aminoester with phenol, 3 (iii) by replacement of sulfoxide group in 2-ethylsulfinyl-5, 8-dimethoxychromone by NHRR

Substituent-controlled domino-Knoevenagel-hetero Diels–Alder reaction—a one-pot synthesis of polycyclic heterocycles

“…Formation of 5 may be rationalized by considering the formation of intermediate 7a, which undergoes intramolecular Michael type addition of the activated aromatic ring (8) (path a, Scheme 1). Similar cyclisation process involving the aldehyde group 10,11,18,22 or using the Knoevenagel condensate 23 To check the effect of the substituent in the allyl part in the intramolecular hetero DielseAlder (IHDA) reaction, compound 1 was alkenylated with cinnamyl bromide 2 (R 3 ¼H, R 4 ¼Ph) to form 3 (R 3 ¼H, R 4 ¼Ph). It was then heated with equimolar amount of 4 in ethanol in the presence of catalytic amount of pyridine, when a pentacyclic compound 6 (R 3 ¼H, R 4 ¼Ph) was obtained in moderate yields (entries 5 and 6).…”

Regio‐ and stereoselective synthesis of 1‐benzopyrano[2,3‐b]pyrrolo[2,3‐d]pyridines: A microwave‐accelerated intramolecular [3+2] cycloaddition reaction of azomethine ylide

“…2‐Alkyl/arylamino‐3‐formylchromone 3 has become an attractive building block for the synthesis of various heterocycles. Synthesis of 3 was achieved directly from 3‐formylchromone 1 [29] or by the rearrangement of nitrone 2 [30, 31]. Use of 3 as a synthon has drawn attention markedly in this decade [32–38].…”

Synthesis of 2,2′-Diaminobischromones Using a Modified Procedure for the Rearrangement of 5-(2-Hydroxyphenyl)isoxazole to 2-Aminochromone

“…The 2-aminochromone class of compounds are important for their antiplatelet activity. 3 Our present interest in the field of 2-aminochromone system 4 gave us an impetus to synthesise 2,2¢-diaminobischromones 3 (Figure 1).…”