Exploring TiO<sub>2</sub> NPs as efficient catalyst for 1,6 Michael addition of 3-methyl-5-pyrazolone on 3-methyl-4-nitro-5-alkenyl isoxazoles and rapid synthesis of 3,3‐bis(indolyl)oxindoles in water
3-methyl-5-pyrazolone on 3-methyl-4-nitro-5-alkenyl isoxazoles and rapid synthesis of 3,3-di(indolyl)indolin-2-ones by reaction of indole on isatin at room temperature in water for the first time. Moderate to good yield was obtained in case of 1, 6 Michael addition reaction and quantitative yield in case of a 3,3‐bis(indolyl)oxindole products. A scale up experiment on gram scale was performed successfully
A wide range of structurally diverse 3,3′-thiopyrrolidonyl spirooxindoles bearing three contiguous stereogenic centers can be smoothly obtained via a domino Michael/cyclization reaction between 3-isothiocyanato oxindoles and 3-methyl-4-nitro-5-alkenyl-isoxazoles with commercially available quinine as the catalyst under mild conditions. The protocol is significantly characterized by high reactivity
DBU-Catalyzed Inter- and Intramolecular Double Michael Addition of Donor–Acceptor Chromone-Pyrazolone/Benzofuranone Synthons: Access to Spiro-Pyrazolone/Benzofuranone-Hexahydroxanthone Hybrids
作者:Qi Di Wei、Yi-Ming Yao、Shun-Qin Chang、Wu-De Yang、Min-Yi Tian、Xiong-Li Liu、Ying Zhou
DOI:10.1055/s-0037-1610728
日期:2020.1
A DBU-catalyzed inter- and intramolecular double Michael addition of donor–acceptor chromone-pyrazolone/benzofuranone synthons and 3-methyl-4-nitro-5-alkenylisoxazoles has been established, which constructed structurally diverse spiro-pyrazolone/benzofuranone-hexahydroxanthone hybrids bearing five consecutive stereocenters in good yields (up to 91%) with high diastereoselectivities (up to >20:1 dr)
An asymmetric, phase-transfer-catalyzed vinylogous conjugate addition–vinylogous cyclization cascade of olefinic azlactones with 4-nitro-5-styrylisoxazoles is reported. In the presence of an l-tert-leucine-derived urea–quaternary ammonium salt as a bifunctional phase-transfer catalyst and KF, two series of valuable optically pure cyclohexenones featuring two and three stereocenters were obtained in
Isatin N,N′-cyclic azomethine imine 1, 3-dipole mediated regio and diastereoselective synthesis of isoxazole-containing spirooxindoles by an abnormal [3 + 2] cycloaddition
An abnormal [3 + 2] cycloaddition with isatin N,N′‑cyclic azomethine imines and styrylisoxazoles for the formation of spirocyclic oxindoles via C(sp3)-H activation and C3 umpolung of quaternary oxindoles has been developed. Various isatin N,N′‑cyclic azomethine imines and styrylisoxazoles underwent in a CNC [3 + 2] cycloaddition with wide substrate scope. Numerous bicyclic spiropyrrolidine oxindoles