It all adds up: The activation of aromatic isoxazoles with a nitro group at the 4‐position has enabled the first regio‐ and diastereoselective trifluoromethylation at the 5‐position of isoxazoles by nucleophilic addition using Me3SiCF3 (see scheme; DMF=N,N′‐dimethylformamide). The process was demonstrated with a broad range of 3,5‐aromatic, heteroaromatic and aliphatic substrates.
所有这些加起来:在4位上带有硝基的芳香异恶唑的活化,使得能够通过Me 3 SiCF 3的亲核加成在异恶唑的5位上进行第一次区域和非对映选择性的三氟甲基化(参见方案; DMF = N ,N'-二甲基甲酰胺)。广泛的3,5-芳族,杂芳族和脂族底物都证明了该方法。
Enantioselective 1,6-Michael addition of anthrone to 3-methyl-4-nitro-5-alkenyl-isoxazoles catalyzed by bifunctional thiourea-tertiary amines
efficient method for the enantioselective 1,6-Michael addition reaction of anthrone to a series of 3-methyl-4-nitro-5-alkenyl-isoxazoles with a bifunctional thiourea-tertiary amine as catalyst is described. This transformation proceeds smoothly with 10 mol % catalyst and provides a series of Michael adducts bearing 3-methyl-4-nitro-isoxazole and anthrone units with good to high enantioselectivities (up
Enantioselective Addition of Diphenylphosphine to 3-Methyl-4-nitro-5-alkenylisoxazoles
作者:Renta Jonathan Chew、Yinhua Huang、Yongxin Li、Sumod A. Pullarkat、Pak-Hing Leung
DOI:10.1002/adsc.201300164
日期:2013.5.3
An enantioselective Michael addition reaction of diphenylphosphine to substituted alkenylisoxazoles has been developed. The reaction proceeds efficiently under mild conditions with high yields (up to 99%) and moderate to excellent enantioselectivities (up to 92%) thus providing a hitherto unavailable direct access to a library of chiral tertiary phosphine‐functionalized isoxazoles.
Chiral Squaramide Catalyzed Enantioselective 1,6-Michael Addition of Pyrazolin-5-ones to Styrylisoxazole Derivatives
作者:Vivek Sharma、Jasneet Kaur、Swapandeep S. Chimni
DOI:10.1002/ejoc.201800589
日期:2018.7.13
The cinchonidine squaramide catalyzed enantioselective 1,6‐Michaeladdition reaction of 3‐methyl‐4‐nitro‐5‐alkenylisoxazoles and pyrazolin‐5‐ones has been developed. Under mild reaction conditions, heterocyclic products that contain both pyrazole and isoxazole moieties were produced in up to 91 % yield with enantiomeric ratios (er) up to 91:9.