Photomechanical Actuation of Ligand Geometry in Enantioselective Catalysis
Photomechanical Actuation of Ligand Geometry in Enantioselective Catalysis
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对映选择性催化中配体几何形状的光机械驱动
DOI：
10.1002/ange.201407494
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发表时间：
2014
影响因子：
--
通讯作者：
Kean Z
中科院分区：
文献类型：
--
作者：
Kean Z
报道了一种催化剂，其将光开关耦合到手性双（膦）配体的联芳基主链，从而允许配体几何形状的光化学操纵而不干扰电子结构。催化剂的活性和选择性的变化，切换时可以归因于分子内的机械力，从而奠定了基础，一类新的催化剂，其选择性可以变化平稳，并在一个有用的范围内通过控制分子应力的催化剂在周转过程中所经历的原位。力的数量级为100 pN的产生，从而导致可测量的变化的不对称赫克芳基化和Trost烯丙基烷基化的对映体选择性。 施加的力和竞争的立体化学途径之间的差分耦合被量化，并发现是更有效的赫克芳基化。
A catalyst that couples a photoswitch to the biaryl backbone of a chiral bis(phosphine) ligand, thus allowing photochemical manipulation of ligand geometry without perturbing the electronic structure is reported. The changes in catalyst activity and selectivity upon switching can be attributed to intramolecular mechanical forces, thus laying the foundation for a new class of catalysts whose selectivity can be varied smoothly and in situ over a useful range by controlling molecular stress experienced by the catalyst during turnover. Forces on the order of 100 pN are generated, thus leading to measurable changes in the enantioselectivities of asymmetric Heck arylations and Trost allylic alkylations. The differential coupling between applied force and competing stereochemical pathways is quantified and found to be more efficient for the Heck arylations.