Enantioselective 1,3-Dipolar Cycloaddition of <i>C</i>,<i>N</i>-Cyclic Azomethine Imines to Unsaturated Nitriles Catalyzed by Ni<sup>II</sup>–Pigiphos
作者:Sandra Milosevic、Antonio Togni
DOI:10.1021/jo401247d
日期:2013.10.4
The asymmetric 1,3-dipolar cycloaddition reaction of C,N-cyclic azomethine imines with small unsaturated nitriles using a dicationic Ni(II) complex containing the chiral triphosphine ligand bis(R)-1-[(Sp)-2-(diphenylphosphino)ferrocenyl]ethyl}cyclohexylphosphine [(R,Sp)-Pigiphos] as a catalyst has been developed. A variety of new chiral cyanopyrazolidines were obtained regio- and diastereoselectively
的不对称1,3-偶极环加成反应Ç,Ñ使用双阳离子的Ni(II)含有手性配体triphosphine双(复杂-环状甲亚胺亚胺与小不饱和腈- [R)-1 - [(小号p)-2- (二苯基膦基)二茂铁基]乙基}环己基[([R ,小号p)-Pigiphos]作为催化剂已经研制成功。区域和非对映选择性地获得了许多新的手性氰基吡唑烷,产率高至优异,对映选择性中等至优异。因此,N-苯甲酰氨基3,4-二氢-6-甲基异喹啉甜菜碱(1a)在1-5 mol%催化剂存在下于室温与丙烯腈反应,以最高84%的收率得到3,4-反式-1-苯甲酰基-4-氰基-2,3-(四氢异喹啉)四氢吡唑(2a),并98%ee。在化合物2a和3,4-反式-1-苯甲酰基-4-氰基-2,3-(6-溴四氢异喹啉)四氢吡唑(2e)的情况下,通过X射线晶体学证实了区域选择性和立体选择性。