The Michael donor–acceptor reactivity of curcumins in the synthesis of diverse multi-functional scaffolds

Organic & Biomolecular Chemistry, Journal Year: 2024, Volume and Issue: 22(7), P. 1346 - 1359

Published: Jan. 1, 2024

Curcumin and its analogs, display Michael donor–acceptor ability with various reactants in the presence of bases, Lewis acids catalysts, under conventional, microwave mechanochemical conditions generate diverse synthetic scaffolds.

Language: Английский

Mechanistic Study on the Asymmetric Cascade Michael Addition of Alkynone and Oxindole Catalyzed by Chiral Guanidine

The Journal of Organic Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: March 26, 2025

Density functional theory (DFT) calculations with the M06-2X-D3 were used to get mechanistic investigation and stereoselectivity of cascade Michael addition alkynone oxindole, catalyzed by a chiral guanidine-amide compound. The reaction proceeded through two-step synergistic process involving sequential C–C C–O bond formation, together an H-shift. Because high energy barriers 33.5 kcal mol−1 (for construction) 41.3 mol–1 construction), was difficult proceed without catalyst. guanidine catalyst facilitated generation enolized oxindole species nucleophilicity, activating both enolate via ion-pairing multiple hydrogen bonding, significantly lowering activation barriers. combination unit sulfonamide backbone created excellent semiclosed environment, promoting asymmetric induction. Due steric effects from ortho- para-substituted iPr groups in SO2Ar, bulky Cy group, backbone, SS-configuration spirocyclization product enantio- diastereoselectivity formed predominantly. E/Z selectivity formation key α,β-unsaturated ketone intermediate influenced catalyst-substrate interactions. Extension alkyl chain at 3-position substrate led more difficult, hindering construction spirooxindoles.

Language: Английский

Diastereoselective synthesis of highly substituted cyclohexanones and tetrahydrochromene-4-ones via conjugate addition of curcumins to arylidenemalonates

Beilstein Journal of Organic Chemistry, Journal Year: 2024, Volume and Issue: 20, P. 2016 - 2023

Published: Aug. 15, 2024

A cascade inter-intramolecular double Michael strategy for the synthesis of highly functionalized cyclohexanones from curcumins and arylidenemalonates is reported. This works in presence aqueous KOH using TBAB as a suitable phase transfer catalyst at room temperature. The are formed major products moderate to excellent yields with complete diastereoselectivity most cases. triple adduct, tetrahydrochromen-4-one, also side product few cases diastereoselectivity.

Language: Английский