Applications of 4,4‘-(Me3Si)2-BINAP in Transition-Metal-Catalyzed Asymmetric Carbon−Carbon Bond-Forming Reactions
摘要:
A recently developed BINAP derivative with trimethylsilyl substituents on the 4- and 4 '-positions of the binaphthyl skeleton, 2,2 '-bis-(diphenylphosphino)-4,4 '-bis(trimethylsilyl)-1,1 '-binaphthyl (tms-BINAP), was used in a variety of transition-metal-catalyzed asymmetric carbon-carbon bond-forming reactions. In pi-allylpalladium-mediated reactions, tms-BINAP gave better enantioselectivity than the unsubstituted BINAP, and the origin of the improved enantioselectivity was gained from an X-ray structural study of [Pd(eta(3)-C3H5)((R)-tms-BINAP)]CIO4.
palladium-catalyzed allylicsubstitutions of a wide range of substrate types and nucleophiles using a bidentate ligand composed of oxazoline and chirally flexible biaryl phosphite elements. This unusually wide substrate scope is shown by experimental and theoretical studies of its η3-allyl and η2-olefin complexes not to be a result of configurational interconversion of the biaryl unit, since the ligand
Novel Chiral Diamino-Oligothiophenes as Valuable Ligands in Pd-Catalyzed Allylic Alkylations. On the “Primary” Role of “Secondary” Interactions in Asymmetric Catalysis
A new class of chiral C2-symmetrical diamino-oligothiophenes is described to be effective in catalyzing Pd-mediated asymmetricallylicalkylations in a highly enantioselective manner. The combination of experimental as well as crystallographic evidence revealed the key role played by sulfur-based heteroaromatic rings in the stereodiscriminating step of the procedure. In particular, unprecedented non-covalent
Enantiomerically pure diamino-bis(tert-thiophene) 1b proved to be a valuable and flexible chiral ligand for Pd- and Zn-catalyzed transformations, allowing for high levels of stereocontrol in asymmetric allylic alkylation (ee up to 99%) and hydrosilylations of prochiral carbonyls (ee up to 97%).
Synthetic and mechanistic studies in enantioselective allylic substitutions catalysed by palladium complexes of a modular class of axially chiral quinazoline-containing ligands
作者:Anne-Marie Carroll、Mary McCarthy、Patrick M. Lacey、Cormac P. Saunders、David J. Connolly、Annette Farrell、Balaji V. Rokade、Richard Goddard、Peter Fristrup、Per-Ola Norrby、Patrick J. Guiry
DOI:10.1016/j.tet.2019.130780
日期:2020.1
The application of palladium complexes of a modular series of axially chiral phosphinamine ligands, the Quinazolinaps, to the enantioselectivealkylation of 1,3-diphenyl-2-propenyl acetate with dimethyl malonate and methyl dimethyl malonate is described. Complete conversions and enantiomeric excesses of up to 91% were obtained. To elucidate the solution structure of these complexes and their dynamic
Turning the Nitrogen Atoms of an Ar<sub>2</sub>
P−CH<sub>2</sub>
−N−N−CH<sub>2</sub>
−PAr<sub>2</sub>
Motif into Uniquely Configured Stereocenters: A Novel Diphosphane Design for Asymmetric Catalysis
作者:Eva Diehl née Knobloch、Reinhard Brückner
DOI:10.1002/chem.201706160
日期:2018.3.7
Hexahydropyridazines with CH2PAr2 groups at both N atoms are newly designed 1,4‐diphosphanes and were synthesized for the first time. Their N atoms assume a single configuration under the influence of stereocenters at C‐5 and C‐6. In the solid state, these N‐atoms bind the CH2PAr2 substituents axially. Combined with Pd0, N,N′‐chiral diphosphanes of this kind catalyzed Tsuji–Trost type allylations of dialkyl malonates
在两个N原子上均具有CH 2 PAr 2基团的六氢哒嗪是新设计的1,4-二膦烷,是首次合成。它们的N原子在C-5和C-6的立体中心的影响下呈单一构型。在固态下,这些N原子轴向结合CH 2 PAr 2取代基。与此类的Pd 0,N,N'-手性二膦烷结合,可有效地与乙酸外消旋1,3-二苯基烯丙基乙酸酯催化二甲基丙二酸酯的Tsuji-Trost型烯丙基化,且ee高达91% 。