Enantioselective Diene Cyclization/Hydrosilylation Catalyzed by Optically Active Palladium Bisoxazoline and Pyridine−Oxazoline Complexes
作者:Nicholas S. Perch、Tao Pei、Ross A. Widenhoefer
DOI:10.1021/jo0003192
日期:2000.6.1
palladium pyridine-oxazoline complex (N-N)Pd(Me)Cl ¿N-N = (R)-(+)-4-isopropyl-2-(2-pyridinyl)-2-oxazoline (R-5b) and NaBAr(4) (5 mol %) catalyzed the asymmetric cyclization/hydrosilylation of 2 and triethylsilane at -32 degrees C for 24 h to form carbocycle S,S-3 in 82% yield (>95% de, 87% ee) as the exclusive product. Asymmetric diene cyclization catalyzed by complex R-5b was compatible with a range
(NN)Pd(Me)Cl(NN =(S,S)-4,4'-di苄基-4,5,4',5'-四氢-2,2'-双恶唑啉的1:1混合物,S-4a)和NaBAr(4)?Ar = 3,5-C(6)H(3)(CF(3))(2)(5 mol%)催化二烯丙基二丙二酸二甲酯的不对称环化/氢化硅烷化反应(2 )和三乙基硅烷在-30摄氏度下反应48小时,以形成甲硅烷基化的碳环(S,S)-trans-1,1-二苯甲氧基-4-甲基-3-¿(三乙基甲硅烷基)甲基环戊烷( S,S-3)(95%de,72%ee)和3,4-二甲基环戊烷-1,1-二羧酸二甲酯(S,S-6)的合并产率为64%。相比之下,钯吡啶-恶唑啉络合物(NN)Pd(Me)Cl = NN =(R)-(+)-4-异丙基-2-(2-吡啶基)-2-恶唑啉( R-5b)和NaBAr(4)(5 mol%)在-32摄氏度下催化2和三乙基硅烷的不对称环化/氢化硅烷化24小时