Department of Chemistry, University of Wisconsin-Madison , 1101 University Avenue, Madison Wisconsin 53706, United States.
J Am Chem Soc. 2014 Jun 4;136(22):7943-53. doi: 10.1021/ja501568k. Epub 2014 May 20.
Condensation reactions of enantiopure bis-3,4-diazaphospholanes (BDPs) that are functionalized with carboxylic acids enable covalent attachment to bead and silica supports. Exposure of tethered BDPs to the hydroformylation catalyst precursor, Rh(acac)(CO)2, yields catalysts for immobilized asymmetric hydroformylation (iAHF) of prochiral alkenes. Compared with homogeneous catalysts, catalysts immobilized on Tentagel resins exhibit similarly high regioselectivity and enantioselectivity. When corrected for apparent catalyst loading, the activity of the immobilized catalysts approaches that of the homogeneous analogues. Excellent recyclability with trace levels of rhodium leaching are observed in batch and flow reactor conditions. Silica-bound catalysts exhibit poorer enantioselectivities.
手性双（3,4-二氮杂膦环）（BDPs）与羧酸官能化的缩合反应能够将其共价连接到珠状和硅胶载体上。将键合的 BDP 暴露于氢甲酰化催化剂前体 Rh(acac)(CO)2 下，可得到用于固定化不对称氢甲酰化（iAHF）的前手性烯烃的催化剂。与均相催化剂相比，键合在 Tentagel 树脂上的催化剂表现出相似的高区域选择性和对映选择性。当对表观催化剂负载量进行校正时，固定化催化剂的活性接近均相类似物的活性。在分批和流动反应器条件下，观察到具有痕量铑浸出的优异可回收性。硅胶结合的催化剂表现出较差的对映选择性。
