Synthesis and Catalytic Properties of Configurationally Stable and Non-racemic Sulfur-Containing Palladacycles
作者:Jairton Dupont、Adriane S. Gruber、Glédison S. Fonseca、Adriano L. Monteiro、Gunter Ebeling、Robert A. Burrow
DOI:10.1021/om000699h
日期:2001.1.1
rac-6b have been isolated as single isomers, whereas rac-5b has been obtained as a mixture of two diastereoisomers (3:1). Variable-temperature 1H NMR showed that the S-t-Bu palladacycle 4b is configurationally stable over a large range of temperatures (from −20 to 100 °C). On the other hand, S-Me analogue 5b undergoes facile sulfur pyramidal inversion with an energy barrier of 18 kcal/mol. Moreover, the
外消旋的硫氯桥联四氢环戊四环(rac - 4b - 6b),其衍生自(1-叔丁基硫烷基乙基)苯,(1-甲基硫烷基乙基)苯和2-(1-叔丁基硫烷基乙基)萘的正钯反应(rac - 1 - 3),已经在使用乙酸钯作为金属化剂良好的产率被合成,并随后用LiCl反应。Palladacycles rac - 4b和rac - 6b已被分离为单一异构体,而rac - 5b获得了两种非对映异构体(3:1)的混合物。可变温度1 H NMR表明,S- t- Bu钯环4b在很大的温度范围(-20至100°C)下具有构型稳定性。另一方面,S-Me类似物5b经历了18 kcal / mol的能垒,易于进行硫磺锥体转化。此外,光学活性的(1-alkylsufanylethyl)苯,(- [R ) - 1和(- [R )- 2,已经分别在分别为91%和97%ee的,制备,由甲基硫醇钠的反应和钠叔-butylthiola