Homogeneous, Supramolecular and Bio-Inspired Catalysis, Van't Hoff Institute for Molecular Sciences University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands.
InCatT B.V., Science Park 904, 1098 XH, Amsterdam, The Netherlands.
Chemistry. 2020 Jul 2;26(37):8214-8219. doi: 10.1002/chem.202000620. Epub 2020 Jun 11.
Regioselective catalytic transformations using supramolecular directing groups are increasingly popular as it allows for control over challenging reactions that may otherwise be impossible. In most examples the reactive group and the directing group are close to each other and/or the linker between the directing group is very rigid. Achieving control over the regioselectivity using a remote directing group with a flexible linker is significantly more challenging due to the large conformational freedom of such substrates. Herein, we report the redesign of a supramolecular Rh-bisphosphite hydroformylation catalyst containing a neutral carboxylate receptor (DIM pocket) with a larger distance between the phosphite metal binding moieties and the DIM pocket. For the first time regioselective conversion of internal and terminal alkenes containing a remote carboxylate directing group is demonstrated. For carboxylate substrates that possess an internal double bond at the Δ-9 position regioselectivity is observed. As such, the catalyst was used to hydroformylate natural monounsaturated fatty acids (MUFAs) in a regioselective fashion, forming of an excess of the 10-formyl product (10-formyl/9-formyl product ratio of 2.51), which is the first report of a regioselective hydroformylation reaction of such substrates.
使用超分子导向基团的区域选择性催化转化越来越受欢迎，因为它可以控制具有挑战性的反应，否则这些反应可能是不可能的。在大多数情况下，反应基团和导向基团彼此靠近，或者导向基团之间的连接基团非常刚性。使用具有柔性连接基团的远程导向基团来控制区域选择性具有更大的挑战性，因为这种底物具有较大的构象自由度。在此，我们报告了一种包含中性羧酸受体（DIM 口袋）的超分子 Rh-双膦氢甲酰化催化剂的重新设计，其中膦金属结合部分和 DIM 口袋之间的距离更大。首次证明了含有远程羧酸导向基团的内部和末端烯烃的区域选择性转化。对于在Δ-9 位置具有内部双键的羧酸底物，观察到区域选择性。因此，该催化剂用于以区域选择性方式氢甲酰化天然单不饱和脂肪酸（MUFAs），形成过量的 10-甲酰基产物（10-甲酰基/9-甲酰基产物比为 2.51），这是此类底物的区域选择性氢甲酰化反应的首次报道。
