Titanocene Dichloride as a Convenient Catalyst for the Diastereoselective Oxidation of 2-Substituted 1,3-Dithianes and 1,3-Dithiolanes
作者:Giorgio Della Sala、Stefania Labano、Alessandra Lattanzi、Consiglia Tedesco、Arrigo Scettri
DOI:10.1055/s-2002-20965
日期:——
Cp2TiCl2 is an efficient catalyst for the diastereoselective mono-oxidation of 2-substituted 1,3-dithianes and 1,3-dithiolanes by tert-butyl hydroperoxide; comparable stereoselectivities and better yields than Ti(i-PrO)4 were obtained. Activities are similar, provided activated 4Å molecular sieves are present in the titanocene-promoted process. Furthermore, Cp2TiCl2 is a more moisture stable compound than Ti(i-PrO)4 and therefore can be used in catalytic amounts of 1 mol%.
Cp2TiCl2 是一种有效的催化剂,用于叔丁基过氧化氢对 2-取代的 1,3-二噻烷和 1,3-二硫杂环戊烷进行非对映选择性单氧化反应;获得了与 Ti(i-PrO)4 相当的立体选择性和更好的产率。如果二茂钛促进的过程中存在活化的 4Å 分子筛,则活性相似。此外,Cp2TiCl2 是一种比 Ti(i-PrO)4 更稳定的化合物,因此可以以 1 mol% 的催化量使用。