Studies on the Chemical Reactions of Some 3‐Substituted‐6,8‐dimethylchromones with Nucleophilic Reagents

Abstract

A variety of 3‐substituted‐6,8‐dimethylchromones have been synthesized and characterized. The chemical reactivity of 3‐substituted‐6,8‐dimethylchromones was studied towards some nucleophiles, namely, S‐benzyldithiocarbazate, o‐phenylenediamine, and cyanoacetamide, and a diversity of products were efficiently synthesized. Reactions of 3‐substituted‐6,8‐dimethylchromones (except 3‐formyl‐6,8‐dimethylchromone), with nucleophilic reagents, usually proceed through nucleophilic attack at C‐2 position followed by different types of heterocyclization depending on the functional group present at C‐3 position. Structures of the newly synthesized products have been established based on elemental analysis and spectral data.

Reactivity of some 3‐substituted‐6,8‐dimethylchromones toward some nucleophilic reagents

“…Elemental microanalyses were performed on a Perkin‐Elmer CHN‐2400 analyzer. 6,8‐Dimethylchromone‐3‐carboxaldehyde ( 1 ), 35 6,8‐dimethylchromone‐3‐carbonitrile ( 2 ) 36 and 6,8‐dimethylchromone‐3‐carboxylic acid ( 3 ), 25 7‐chloro‐4‐hydrazinoquinoline 26 and 5,6‐diphenyl‐3‐hydrazino‐1,2,4‐triazine 27 were prepared according to the reported methods.…”

“…In some cases, the presence of methyl groups in the benzo‐rings alter the reactivity of substituted chromones toward some nucleophilic reagents 23–25 . In the previous work, 25 some 3‐substituted‐6,8‐dimethylchromones reacted with certain nucleophilic reagents. The present work is directed to investigate the reactivity of 6,8‐dimethylchromone derivatives 1 ‐ 5 (Figure 1) toward some selected nucleophilic reagents namely 3‐amino‐1,2,4‐triazole, 2‐aminobenzimidazole, 7‐chloro‐4‐hydrazinoquinoline 26 and 5,6‐diphenyl‐3‐hydrazino‐1,2,4‐triazine 27 …”

“…3‐Substituted chromones reacted with binucleophilic reagents giving a diversity of heterocyclic systems 20–22 . In some cases, the presence of methyl groups in the benzo‐rings alter the reactivity of substituted chromones toward some nucleophilic reagents 23–25 . In the previous work, 25 some 3‐substituted‐6,8‐dimethylchromones reacted with certain nucleophilic reagents.…”

Synthetic Routes to Coumarin(Benzopyrone)-Fused Five-Membered Aromatic Heterocycles Built on the α-Pyrone Moiety. Part II: Five-Membered Aromatic Rings with Multi Heteroatoms

“…The transformation of three-substituted chromone to chromeno[4,3- c ]pyrazol-4(2 H )-ones was within the scope of interest of Ibrahim’s research group [ 33 , 34 , 35 , 36 ]. In 2008, they studied the ring transformation of chromone-3-carboxylic acid ( 20 ) under the reaction with 2-cyanoacetohydrazide or the hydrazine hydrate as the nucleophile to give the corresponding chromeno[4,3- c ]pyrazol-4(2 H )-one ( 9a ) ( Scheme 7 ) [ 33 ].…”

Construction, characterization, and antimicrobial evaluation of the novel heteroannulated chromeno[2′′,3′′:6′,5′]pyrido[2′,3′‐d] [1,3] thiazolo[3,2‐a]pyrimidines

“…[21][22][23][24] The presence of electron withdrawing substituents in position 3 of the chromone moiety activate the C-2 position toward nucleophilic reagents providing a diversity of products based on the functional group at position 3 as well as the used nucleophile. [25][26][27][28][29][30] The current work is directed to synthesis a new series of annulated chromenopyridothiazolopyrimidines and investigate their antimicrobial activity.…”