253308-74-6Relevant academic research and scientific papers
Chiral Cyclopentadienyl Cobalt(III) Complexes Enable Highly Enantioselective 3d-Metal-Catalyzed C-H Functionalizations
Ozols, Kristers,Jang, Yun-Suk,Cramer, Nicolai
, p. 5675 - 5680 (2019)
The synthesis of a set of cobalt(III)-complexes equipped with trisubstituted chiral cyclopentadienyl ligands is reported, and their steric and electronic parameters are mapped. The application potential of these complexes for asymmetric C-H functionalizations with 3d-metals is shown by the synthesis of dihydroisoquinolones from N-chlorobenzamides with a broad range of alkenes. The transformation proceeds with excellent enantioselectivities of up to 99.5:0.5 er and high regioselectivities. The observed values outperform the best rhodium(III)-based methods for this reaction type. Moreover, challenging substrates such as alkyl alkenes also react with high regio- and enantioselectivities.
Rhodium Catalysts with a Chiral Cyclopentadienyl Ligand Derived from Natural R-Myrtenal
Kolos, Andrey V.,Nelyubina, Yulia V.,Perekalin, Dmitry S.,Pototskiy, Roman A.
, p. 6019 - 6025 (2020/09/21)
A new chiral cyclopentadiene CpmyrH was synthesized from the natural terpene (R)-myrtenal in 5 steps and about 40 % total yield. The key step was the reaction of vinyl-dibromocyclopropane derivative with MeLi which provided the diene Cpmyr
Mild complexation protocol for chiral CpxRh and Ir complexes suitable for: In situ catalysis
Audic,Wodrich,Cramer
, p. 781 - 787 (2019/01/24)
A practical complexation method for chiral cyclopentadienyl (Cpx) iridium and rhodium complexes is described. The procedure uses the free CpxH with stable and commercially available rhodium(i) and iridium(i) salts without base or additive. The conditions are mild and do not require the exclusion of air and moisture. A salient feature is the suitability for in situ complexations enhancing the user-friendliness of Cpx ligands in asymmetric catalysis. DFT-calculations confirm an intramolecular proton abstraction pathway by either the bound acetate or methoxide. Furthermore, the superior facial selectivity of the proton abstraction step enabled the development of TMS-containing trisubstituted Cpx ligands which display improved enantioselectivities for the benchmarking dihydroisoquinolone synthesis.
General Enantioselective C?H Activation with Efficiently Tunable Cyclopentadienyl Ligands
Jia, Zhi-Jun,Merten, Christian,Gontla, Rajesh,Daniliuc, Constantin G.,Antonchick, Andrey P.,Waldmann, Herbert
supporting information, p. 2429 - 2434 (2017/02/23)
Cyclopentadienyl (Cp) ligands enable efficient steering of various transition-metal-catalyzed transformations, in particular enantioselective C?H activation. Currently only few chiral Cp ligands are available. Therefore, a conceptually general approach to
Stereoselective photoinduced electrocyclic ring closure of aromatic enehydrazides. Asymmetric synthesis of 3-aryl dihydroisoquinolones and tetrahydroisoquinolines
Dubois, Mélanie,Deniau, Eric,Couture, Axel,Grandclaudon, Pierre
, p. 7140 - 7147 (2012/08/28)
A flexible route for the stereoselective synthesis of a variety of 3-aryl dihydroisoquinolones and tetrahydroisoquinolines has been developed. The key step is a diastereoselective photoinduced 6π-electrocyclic ring closure of enantiopure aromatic enehydrazides via a 1,4-remote asymmetric induction. N-N bond cleavage to release the chiral appendage from the preliminary annulated compounds and/or concomitant reduction of the lactam carbonyl group completed the synthesis of the title compounds.
Asymmetric synthesis of 4-hydroxy-3-phenyltetrahydroisoquinoline derivatives using enantiopure sulfinimines (N-sulfinyl imines)
Davis, Franklin A.,Andemichael, Yemane W.
, p. 8627 - 8634 (2007/10/03)
Addition of lateral lithiated amides and phthalide anions to enantiopure sulfinimines (N-sulfinyl imines) represents a new approach for the asymmetric synthesis of 3-substituted isoquinolones and 3-substituted 4-hydroxy isoquinolones, respectively, important chiral building blocks for isoquinoline alkaloid synthesis. In one example 3-phenylisoquinolone (-)-15b was prepared in >95% ee by treatment of amide ion 10b with sulfinimine (S)- (+)-11 and subsequent deprotection of the N-sulfinyl auxiliary and cyclization. Oxaziridine-mediated hydroxylation of the anion of 16 afforded 4-hydroxy isoquinolone 19, which was transformed into 4-hydroxy-3- phenyltetrahydroisoquinoline (-)-22. In another approach 22 was prepared more directly by addition of phthalide ion 26 to (S)-(+)-11, creating the two stereogenic centers simultaneously. The selectivity proved to be highly counterion dependent.
