496789-06-1Relevant articles and documents
Tandem Iridium Catalysis as a General Strategy for Atroposelective Construction of Axially Chiral Styrenes
He, Ying,Liu, Peng,Min, Xiao-Long,Qi, Xiaotian,Wang, Jie,Yi, Wenbin
supporting information, p. 10686 - 10694 (2021/07/26)
Axially chiral styrenes are of great interest since they may serve as a class of novel chiral ligands in asymmetric synthesis. However, only recently have strategies been developed for their enantioselective preparation. Thus, the development of novel and efficient methodologies is highly desirable. Herein, we reported the first tandem iridium catalysis as a general strategy for the synthesis of axially chiral styrenes enabled by Asymmetric Allylic Substitution-Isomerization (AASI) using cinnamyl carbonate analogues as electrophiles and naphthols as nucleophiles. In this approach, axially chiral styrenes were generated through two independent iridium-catalytic cycles: iridium-catalyzed asymmetric allylic substitution and in situ isomerization via stereospecific 1,3-hydride transfer catalyzed by the same iridium catalyst. Both experimental and computational studies demonstrated that the isomerization proceeded by iridium-catalyzed benzylic C-H bond oxidative addition, followed by terminal C-H reductive elimination. Amid the central-to-axial chirality transfer, the hydroxyl of naphthol plays a crucial role in ensuring the stereospecificity by coordinating with the Ir(I) center. The process accommodated broad functional group compatibility. The products were generated in excellent yields with excellent to high enantioselectivities, which could be transformed to various axially chiral molecules.
Cobalt-Catalyzed Allylic Alkylation Enabled by Organophotoredox Catalysis
Takizawa, Koji,Sekino, Tomoyuki,Sato, Shunta,Yoshino, Tatsuhiko,Kojima, Masahiro,Matsunaga, Shigeki
supporting information, p. 9199 - 9203 (2019/06/04)
Co-catalyzed allylic substitution reactions have received little attention, arguably because of the lack of any known advantage of Co catalysis over either Rh or Ir catalysis. Described here is a general and regioselective Co-catalyzed allylic alkylation using an in situ catalyst activation by organophotoredox catalysis. This noble-metal-free catalytic system exhibits unprecedentedly high reactivities and regioselectivities for the allylation with an allyl sulfone, for the first time, representing the unique synthetic utility of the Co-catalyzed method compared to the related Rh- and Ir-catalyzed reactions.
Catalytic allylic arylation of cinnamyl carbonates over palladium nanoparticles supported on a thermoresponsive polymer in water
Lee, Yongwoo,Shabbir, Saira,Lee, Sinyoung,Ahn, Hyunsoek,Rhee, Hakjune
, p. 3579 - 3583 (2015/06/25)
Poly(NIPAM-co-4-VP) undergoes a phase transition at the low critical solution temperature with a change from the hydrophilic to the hydrophobic core in a hydrophilic solvent. Palladium nanoparticles supported on such a thermoresponsive polymer support were demonstrated to catalyze the Tsuji-Trost reaction for the arylation of various cinnamyl carbonates by arylboronic acids. Therefore, a protocol developed using mild reaction conditions demonstrates the recyclability of the catalyst in an eco-friendly solvent such as water.
A highly enantio- and diastereoselective molybdenum-catalyzed asymmetric allylic alkylation of cyanoesters
Trost, Barry M.,Miller, John R.,Hoffman Jr., Christopher M.
supporting information; experimental part, p. 8165 - 8167 (2011/07/08)
An efficient molybdenum-catalyzed asymmetric allylic alkylation (Mo-AAA) of cyanoester nucleophiles is reported. A number of highly functionalized branched cyanoesters containing a quaternary carbon stereocenter with a vicinal tertiary stereocenter are obtained. This method generates a number of functionalized cyanoesters in excellent yield and chemoselectivity in good to excellent diastereoselectivity and enantioselectivity.
Application of iridium catalyzed allylic substitution reactions in the synthesis of branched tryptamines and homologues via tandem hydroformylation- Fischer indole synthesis
Bondzic, Bojan P.,Farwick, Andreas,Liebich, Jens,Eilbracht, Peter
supporting information; experimental part, p. 3723 - 3731 (2009/02/05)
Combination of enantioselective allylation reactions with a tandem hydroformylation-Fischer indole synthesis sequence as a highly diversity-oriented strategy for the synthesis of tryptamines and homologues was explored. This modular approach allows the su
A novel access to tetrahydro-β-carbolines via one-pot hydroformylation/fischer indole synthesis: Rearrangement of 3,3- spiroindoleninium cations
Bondzic, Bojan P.,Eilbracht, Peter
supporting information; experimental part, p. 3433 - 3436 (2009/05/07)
(Chemical Equation Presented) The two component one-pot hydroformylation/Fischer indole synthesis sequence of 2,5 dihydropyrroles and phenyl hydrazines allows a facile and convenient access to tetrahydro-β- carbolines in moderate to good yields.
Enantioselective iridium-catalyzed allylic amination of ammonia and convenient ammonia surrogates
Pouy, Mark J.,Leitner, Andreas,Weix, Daniel J.,Ueno, Satoshi,Hartwig, John F.
, p. 3949 - 3952 (2008/02/11)
Iridium-catalyzed, asymmetric allylation of ammonia as a nucleophile occurs with stereoselectivity to form a symmetric dialiylamine, and related allylation of the inexpensive ammonia equivalent potassium trifluoroacetamide or the highly reactive ammonia equivalent lithium ditert-butyliminodicarboxylate forms a range of conveniently protected, primary, a-branched allylic amines in high yields, high branched-to-linear regioselectivities, and high enantiomeric excess. The reactions of ammonia equivalents were conducted with a catalyst generated from a phosphoramidite containing a single stereochemical element.
Enantioselective allylation of aromatic amines after in situ generation of an activated cyclometalated iridium catalyst
Shu, Chutian,Leitner, Andreas,Hartwig, John F.
, p. 4797 - 4800 (2007/10/03)
Highly regio- and enantioselective allylation of aromatic amines is observed when a cyclometalated Ir-phosphoramidite complex is generated in situ (see scheme). The active catalyst can be formed from [{Ir(cod)Cl}2] and ligand L with a volatile alkylamine prior to addition of the reagents or upon use of a tertiary amine additive.
Regio- and enantioselective allylic amination of achiral allylic esters catalyzed by an iridium-phosphoramidite complex
Ohmura, Toshimichi,Hartwig, John F.
, p. 15164 - 15165 (2007/10/03)
A new catalytic asymmetric process, the iridium-catalyzed enantioselective allylic amination of (E)-cinnamyl and terminal aliphatic allylic carbonates, was developed by exploring complexes of chiral phosphoramidites. The reaction provided branched secondary and tertiary allylic amines in high yields with excellent regio- and enantioselectivity (13 examples over 94% ee). Although the reactions in polar solvent such as DMF, EtOH, and MeOH were fast, they gave low enantiomeric excesses. In contrast, reactions in THF displayed the most suitable balance of rate and enantioselectivity. Both the binaphthol unit and the disubstituted amine in the phosphoramidite affected reactivity and selectivity, and complexes of O,O′-(R)-(1,1′-dinaphthyl-2,2′-diyl)-N,N′-di-(R,R)-1-phenylethylphosphoramidite provided the highest reactivity and selectivity. Primary and cyclic secondary amines reacted at room temperature, and acyclic diethylamine reacted at 50 °C. p-Methoxy-substituted cinnamyl carbonate reacted similarly to the unsubstituted cinnamyl carbonate, but the o-methoxy-substituted substrate gave lower enantiomeric excess. High ee's were also observed for the products from the reaction of furanyl- and alkyl-substituted (E)-allylic carbonates. Copyright
