Institut für Organische Chemie und Biochemie, Freiburg Institute for Advanced Studies (FRIAS), Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, 79104 Freiburg, Germany.
Chemistry. 2010 Feb 22;16(8):2470-8. doi: 10.1002/chem.200902553.
A library of monodentate phosphane ligands, each bearing a guanidine receptor unit for carboxylates, was designed. Screening of the library gave some excellent catalysts for regioselective hydroformylation of beta,gamma-unsaturated carboxylic acids. A terminal alkene, but-3-enoic acid, was hydroformylated with a linear/branched (l/b) regioselectivity up to 41. An internal alkene, pent-3-enoic acid was hydroformylated with regioselectivity up to 18:1. Further substrate selectivity (e.g., acid vs. methyl ester) and reaction site selectivity (monofunctionalization of 2-vinylhept-2-enoic acid) were also achieved. Exploration of the structure-activity relationship and a practical and theoretical mechanistic study gave us an insight into the nature of the supramolecular guanidinium-carboxylate interaction within the catalytic system. This allowed us to identify a selective transition-state stabilization by a secondary substrate-ligand interaction as the basis for catalyst activity and selectivity.
设计了一个单齿膦配体库，每个配体都带有一个胍受体单元，用于羧酸。对该库进行筛选，得到了一些用于β，γ-不饱和羧酸区域选择性加氢甲酰化的优秀催化剂。末端烯烃，丁-3-烯酸，以高达 41 的线性/支化（l/b）区域选择性加氢甲酰化。内烯烃，戊-3-烯酸，以高达 18:1 的区域选择性加氢甲酰化。还实现了进一步的底物选择性（例如，酸与甲酯）和反应位点选择性（2-乙烯基庚-2-烯酸的单官能化）。对结构-活性关系的探索以及实际和理论的机理研究使我们深入了解了催化体系中超分子胍-羧酸相互作用的性质。这使我们能够确定通过次级底物-配体相互作用选择性地稳定过渡态是催化剂活性和选择性的基础。
