The First Complete Identification of a Diastereomeric Catalyst−Substrate (Alkoxide) Species in an Enantioselective Ketone Hydrogenation. Mechanistic Investigations
作者:Christopher J. A. Daley、Steven H. Bergens
DOI:10.1021/ja0102991
日期:2002.4.1
structures of the major diastereomer catalyst-alkoxide complexes (5, 8, and 10) were unambiguously determined by variable-temperature NMR spectroscopy. The major diastereomers (5, 8, and 10) had the same absolute configuration as the major product enantiomers from the catalytic hydrogenation of 2, 3, and 4 with 1 as catalyst. The ratio of major to minor alkoxide diastereomers was similar to the ee of
二烷基 3,3-二甲基草酰乙酸酮底物(2、3 和 4;分别为烷基 = Me、(i)Pr 和 (t)Bu)的对映选择性氢化由 [Ru((R)-BINAP) 催化(H)(MeCN)(n)(sol)(3-n)](BF(4)) (1, n = 0-3, sol = THF 或 MeOH, (R)-BINAP = (R)-2 ,2'-双(二苯基膦基)-1,1'-联萘)在高达 82% ee (R) 中。活性催化剂 1 与 1 当量底物(2、3 或 4)在 THF 或 MeOH 溶液中的反应形成非对映异构催化剂-醇盐配合物 [Ru((R)-BINAP)(MeCN)(OCH(CO(2) R)-(C(CH(3))(2)CO(2)R))](BF(4)) (5/6 R = Me, 8/9 R = (i)Pr, 10 R = (t)Bu,分别)通过氢化物加成到酮羰基碳和钌加成到氧。主要非对映异构体 5、8、和 10)