Electronic tuning of the PNNP ligand for the asymmetric cyclopropanation of olefins catalysed by [RuCl(PNNP)]+

Cationic ruthenium complexes of the type [RuCl(L)(PNNP)]⁺ (L=OEt₂, OH₂), where PNNP is the CF₃-subsituted PNNP ligand N,N′-bis[o-(bis(4-trifluoromethylphenyl)phosphino)benzylidene]-(1S,2S)-diaminocyclohexane 1b, catalyse the asymmetric cyclopropanation of styrene, α-Me-styrene, and 1-octene with ethyl diazoacetate. These complexes are more active and give higher cis- and enantioselectivities than their analogues containing the unsubstituted ligand 1a. Thus, [RuCl(OEt₂)(1b)]PF₆ cyclopropanates α-Me-styrene with 85% cis selectivity and 86% ee in 94% isolated yield.     

Titanium cis‐1,2‐Diaminocyclohexane (cis‐DACH) Salalen Catalysts for the Asymmetric Epoxidation of Terminal Non‐Conjugated Olefins with Hydrogen Peroxide

Chiral Ti salalen complexes catalyze the asymmetric epoxidation of terminal non‐conjugated olefins with hydrogen peroxide. Modular ligands based on cis‐1,2‐diamino‐cyclohexane (cis‐DACH) were developed, giving high yields and enantiomeric excesses (ee, up to 96 %) at catalyst loadings as low as 0.1–0.5 mol %, and even under solvent‐free conditions.     

Selective Palladium‐Catalyzed Aminocarbonylation of Olefins to Branched Amides

A general and efficient protocol for iso‐selective aminocarbonylation of olefins with aliphatic amines has been developed for the first time. Key to the success for this process is the use of a specific 2‐phosphino‐substituted pyrrole ligand in the presence of PdX₂ (X=halide) as a pre‐catalyst. Bulk industrial and functionalized olefins react with various aliphatic amines, including amino‐acid derivatives, to give the corresponding branched amides generally in good yields (up to 99 %) and regioselectivities (b/l up to 99:1).     

Hydrazide‐Catalyzed Polyene Cyclization: Asymmetric Organocatalytic Synthesis of cis‐Decalins

Polyene cyclizations offer rapid entry into terpenoid ring systems. Although enantioselective cyclizations of (E)‐polyenes to form trans‐decalin ring systems are well precedented, highly enantioselective cyclizations of (Z)‐polyenes to form the corresponding cis‐decalins have not been reported. Here, we describe the first application of iminium catalysis to the initiation of polyene cyclizations. Ethyl 1,2‐diazepane‐1‐carboxylate catalyzes the cyclization of polyenes bearing enal initiators. Moreover, chiral bicyclic hydrazides catalyze the cyclizations of (Z)‐polyene substrates to form cis‐decalins with enantioselectivities of up to 97:3 er. DFT calculations suggest the catalysts promote the reaction by stabilizing positive charge as it develops during the bicyclization.     

Towards the Development of a Selective Ruthenium‐Catalyzed Hydroformylation of Olefins

The ruthenium‐catalyzed hydroformylation of 1‐ and 2‐octene to give preferentially the corresponding linear aldehyde is reported. The catalyst system comprising of Ru₃(CO)₁₂ and an imidazole‐substituted monophosphine ligand allows for high chemo‐ and regioselectivity. The hydroformylation proceeds with unprecedented rates for a ruthenium‐based catalyst.     

水溶性配合物[RuCl2(TPPTS)2]2催化卤代硝基苯选择性加氢

以合成的水溶性钌配合物[RuC l2(TPPTS)2]2作为催化剂,用于水/有机两相体系中催化卤代硝基苯中硝基的选择性加氢反应.以对-氯硝基苯为底物,考察了反应温度、氢气压力、催化剂浓度、水溶液的pH值等对对-氯硝基苯转化率和生成对-氯苯胺选择性的影响.在100℃,氢气压力3.0 MPa时,反应6h,对-氯硝基苯转化率可达100%,生成对-氯苯胺的选择性可达95.2%.该催化剂对其他卤代硝基苯的加氢反应也表现出较高的催化活性.     

The Origin of Anti‐Markovnikov Regioselectivity in Alkene Hydroamination Reactions Catalyzed by [Rh(DPEphos)]+

The development of regioselective anti‐Markovnikov alkene's hydroamination is a long‐standing goal in catalysis. The [Rh(COD)(DPEphos)]⁺ complex is the most general and regioselective group 9 catalyst for such a process. The reaction mechanism for intermolecular hydroamination of alkenes catalyzed by [Rh(DPEphos)]⁺ complex is analyzed by means of DFT calculations. Hydroamination (alkene vs. amine activation routes) as well as oxidative amination pathways are analyzed. According to the computational results the operating mechanism can be generally described by alkene coordination, amine nucleophilic addition, proton transfer through the metal center and reductive elimination steps. The mechanism for the formation of the oxidative amination side product goes via a β‐elimination after the nucleophilic addition and metal center protonation steps. The origin of the regioselectivity for the addition process (Markovnikov vs. anti‐Markovnikov additions) is shown to be not charge but orbitally driven. Remarkably, η² to η¹ slippage degree on the alkene coordination mode is directly related to the regioselective outcome.     

Water,an Essential Element for a ZnII‐Catalyzed Asymmetric Quinone Diels‐Alder Reaction: Multi‐Selective Construction of Highly Functionalized cis‐Decalins

A Zn^II complex of a C₂‐chiral bisamidine‐type sp²N bidentate ligand ( L _R ) possessing two dioxolane rings at both ends catalyzes a highly efficient quinone asymmetric Diels‐Alder reaction (qADA) between o‐alkoxy‐p‐benzoquinones and 1‐alkoxy‐1,3‐butadienes to construct highly functionalized chiral cis‐decalins, proceeding in up to a >99:1 enantiomer ratio with a high generality in the presence of H₂O (H₂O:Zn^II=4–6:1). In the absence of water, little reaction occurs. The loading amount of the chiral ligand can be minimized to 0.02 mol % with a higher Zn/ L _R ratio. This first success is ascribed to a supramolecular 3D arrangement of substrates, in which two protons of an “H₂O‐Zn^II” reactive species make a linear hydrogen bond network with a dioxolane oxygen atom and one‐point‐binding diene; the Zn^II atom captures the electron‐accepting two‐points‐binding quinone fixed on the other dioxolane oxygen atom via an n‐π* attractive interaction. The mechanisms has been supported by ¹H NMR study, kinetics, X‐ray crystallographic analyses of the related Zn L _R complexes, and ligand and substrate structure‐reactivity‐selectivity relationship.