Cascade Michael-Aldol reaction: efficient annulation of sulfonamide chalcones into novel cyclohexenones under solvent-free conditions

Abstract

A simple, convenient and efficient synthesis of novel sulfonamide cyclohexenones from differently substituted sulfonamide chalcones has been developed. Syntheses of cyclohexenones have been achieved via cascade Michael-Aldol reaction under solvent free condition. This process features mild and solvent-free synthesis of the titled compounds with high yields (18 examples, up to 95% yield). The synthesized scaffold is a promising intermediate for the further transformation into various heterocyclic compounds.

Synthesis, in vitroandin silicoBiological Studies of Sulfonamide Chalcones as Esterase Inhibitors

“…The structures of synthesized compounds were approved by the spectral methods ( 1 H/ 13 C NMR, mass and elemental analysis). Both analytical and spectral data of all the synthesized compounds were in full agreement with the proposed structures and literature [25–29] . The trans ‐geometry of the sulfonamide chalcones 1 – 9 double bond was evident by the large olefinic coupling constant between the relevant signals in the 1 H NMR spectrum ( J =15.2–16.2 Hz).…”

“…Compounds (1-5 and 7-9) were synthesized according to the previous literature. [25][26][27][28][29] The synthesis of the compound 6 is being reported for the first time in this work.…”

Chitosan-MgO Nanocomposite: One Pot Preparation and Its Utility as an Ecofriendly Biocatalyst in the Synthesis of Thiazoles and [1,3,4]thiadiazoles

“…In the IR spectra, two absorption bands in the range of υ = 3212–3268 cm −1 and 1578–1600 cm −1 were revealed owing to the presence of (N–H) and (C=N) groups, respectively. Also, the sulfonamide group (SO 2 NH) showed asymmetric and symmetric stretching signals at υ = 1336–1379 cm −1 and 1136–1161 cm −1 , respectively [22]. In 1 H NMR spectra two methyl groups bordering to hydrazone moiety (CH 3 –C=N–NH) [23] and a thiazole ring [24] were observed as singlet signals at δ = 2.35–2.43 and 2.43–2.59 ppm, respectively, while the NH proton of the sulfonamide group [22] was resonated at δ = 10.43–10.92 ppm.…”

Synthesis, Structural and Biological Properties of the Ring-A Sulfonamido Substituted Chalcones: A Review

“…A number of synthetic routes have been reported for synthesis of the o / m / p -(sulfonamido)chalcones and their general synthesis involves the Claisen-Schmidt aldol condensation of o / m / p -sulfonamidoacetophenone precursors with benzaldehyde derivatives in the presence of an acid [ 20 ] or base [ 2 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 21 , 22 , 23 , 24 , 25 ] followed by spontaneous in situ dehydration of the incipient β-hydroxyketone intermediates. The sulfonamidoacetophenones 2 are, in turn, prepared from the corresponsing o / m / p -aminoacetophenones 1 with alkyl/arylsulfonyl chloride derivatives in the presence of an amine as a base in the absence or presence of a solvent ( Scheme 1 ).…”

“…No traces of the bisarylsulfonamide derivatives were detected or isolated from the reaction mixtures. Sulfonamidochalcones are interesting synthetic intermediates as they provide a versatile platform for the synthesis of bioactive scaffolds such as cyanopyridines, isoxazoles, pyrazoles and pyrimidin-2-thiones [25]. The presence of the ambident electrophilic α,βunsaturated carbonyl framework and its proximity to the nucleophilic ortho-sulfonamido group have long been exploited as templates for the base-mediated cyclization to afford the 2-aryl-1-(alkyl/arylsufonyl)-2,3-dihydroquinolin-4(1H)-ones [27][28][29] with increased A series of the 5-styryl-2-aminochalcone hybrids 7a-h were previously subjected to 1.2 equiv.…”