合成了在第四和第六位含有甲基,乙基,二异丁基和二异丙基取代基的各种二烷基二苯并噻吩,并比较了它们在NiMo / Al 2 O 3上的反应性工业催化剂。在间歇反应器中在573 K和5 MPa的总压力下进行研究。动力学研究和竞争反应表明,催化剂表面的吸附不是决定其转化速率的步骤。提出加氢脱硫是在硫化合物的一个芳环部分氢化后通过平行反应网络进行的。不同的二苯并噻吩衍生物的反应性变化与硫原子附近烷基产生的空间位阻密切相关。而且,在我们的反应条件下,4,6-二异丙基二苯并噻吩显示出非常低的反应性,并且空间效应导致脱硫的消失。
Synthesis of new sulfur-containing oxazoline ligands and their use in palladium-catalyzed allylic substitution
作者:Arnaud Voituriez、Emmanuelle Schulz
DOI:10.1016/s0957-4166(02)00829-7
日期:2003.2
New chiral sulfur-containing ligands have been prepared and fully characterized. Their structure includes a dibenzothiophene or benzothiophene ring as backbone, where the sulfur atom is enclosed in a strong pi-donor structure. The chirality was introduced by oxazoline moieties placed near the sulfur atom. These ligands have been successfully tested in asymmetric palladium-catalyzed allylic substitutions leading to products with ee of up to 77%. (C) 2003 Elsevier Science Ltd. All rights reserved.