Pd-Catalyzed Carboetherification of β,γ-Unsaturated Oximes: A Novel Approach to Δ2-Isoxazolines
摘要:
A novel route to the synthesis of Delta(2)-isoxazoline derivatives is described. Reaction of beta,gamma-unsaturated oximes with aryl bromides via palladium-catalyzed carboetherification affords 3,5-disubstituted Delta(2)-isoxazolines in good yields. The use of Xantphos as ligand is crucial for the transformation. The carboetherification products can be further converted to beta-hydroxy ketones in the presence of Fe powder and NH(4)Cl.
highly efficient Pd/Xiang-Phos catalyzedenantioselective carboetherification of alkenyl oximes with either aryl or alkenyl halides, delivering various chiral 3,5-disubstituted and 3,5,5-trisubstituted isoxazolines in good yields with up to 97 % ee. The sterically bulky and electron-rich (S,Rs)-NMe-X2 ligand is responsible for the excellent reactivities and enantioselectivities. The salient features of this
Reduction of Δ<sup>2</sup>-Isoxazolines to β-Hydroxy Ketones with Iron and Ammonium Chloride as Reducing Agent
作者:Dahong Jiang、Yuanwei Chen
DOI:10.1021/jo801831c
日期:2008.11.21
A detailed study of a procedure for the selective reduction of Delta(2)-isoxazolines to the corresponding beta-hydroxy ketones is reported. The use of iron and ammonium chloride as the reducing agent in the presence of water results in a facile and chemoselective protocol for the preparation of beta-hydroxy ketones, including the conjugated beta-hydroxy ketones.