Chiral phosphine–phosphite ligands in the enantioselective 1,4-addition of Grignard reagents to α,β-unsaturated carbonyl compounds
作者:Qaseem Naeemi、Tobias Robert、Darius P. Kranz、Janna Velder、Hans-Günther Schmalz
DOI:10.1016/j.tetasy.2011.04.018
日期:2011.4
phosphine–phosphite ligands was evaluated in the Cu-catalyzed asymmetric 1,4-addition of Grignard reagents to cyclopentenone, cycloheptenone and 5,6-dihydro-2H-pyran-2-one. TADDOL-based ligands 1a and 1b with a bulky substituent at the ortho-position to the chiral phosphite moiety gave rise to the 1,4-addition products with high enantioselectivities (up to 93% ee). In addition to ethyl-MgBr (as a standard
在铜催化的格氏试剂对环戊烯酮,环庚烯酮和5,6-二氢-2 H-吡喃-2-酮的不对称1,4-加成反应中,评估了手性膦-亚磷酸酯配体库。在手性亚磷酸酯部分的邻位具有大取代基的基于TADDOL的配体1a和1b产生具有高对映选择性(至多93%ee)的1,4-加成产物。除了乙基-MgBr(作为标准的烷基亲核试剂)之外,还可以使用苯基-和异丙烯基-MgBr。就环戊烯酮而言,使用氯三甲基硅烷作为添加剂可提高区域选择性和对映选择性。