Synthesis of isoxazolidines and benzisoxazolines
The oxidative intramolecular bromo-amination of various N-alkenyl sulfonamides and N-alkenoxyl sulfonamides via umpolung of alkali metal bromides occurred exo-selectively to generate pyrrolidines and isoxazolidines in high yields with good diastereoselectivities. This method provided the desired products with a low amount of organic waste.
K. Moriyama, Y. Izumisawa, H. Togo, J. Org. Chem., 2011, 76, 7249-7255.
A chiral Ti(IV) catalyst can be successfully utilized in the asymmetric 1,3-dipolar cycloaddition reactions between various nitrones and acrolein to give the corresponding endo cycloadducts (isoxazolidines) with high to excellent enantioselectivities.
T. Kano, T. Hashimoto, K. Maruoka, J. Am. Chem. Soc., 2005, 70, 11926-11927.
A catalyst composed of Pd(OAc)2 and S-Phos allows the conversion of aryl chlorides as electrophiles in Pd-catalyzed alkene carboamination and carboetherification, minimizes N-arylation, and prevents formation of regiosisomieric mixtures. Various heterocycles, including pyrrolidines, isoxazolidines, tetrahydrofurans, and pyrazolidines, are efficiently generated with this method.
B. R. Rosen, J. E. Ney, J. P. Wolfe, J. Org. Chem., 2010, 75, 2756-2759.
A broad range of substituted benzisoxazolines have been synthesized by a mild [3 + 2] cycloaddition of nitrones and arynes. The process tolerates various functional groups.
C. Lu, A. V. Dubrovskiy, R. C. Larock, J. Org. Chem., 2012, 77, 2279-2284.