41822-67-7Relevant academic research and scientific papers
Enantioselective [1,2] Wittig rearrangement using an external chiral ligand
Tomooka, Katsuhiko,Yamamoto, Kyoko,Nakai, Takeshi
, p. 3741 - 3743 (1999)
Even with only a catalytic amount of chiral bis(dihydrooxazole) 1 as external ligand, the rearrangement of benzyl ethers to alcohols [Eq. (1)] proceeds with high enantioselectivity (over 60 % ee). This reaction represents the first example of an enantiose
Enantiomerically Enriched α-Borylzinc Reagents by Nickel-Catalyzed Carbozincation of Vinylboronic Esters
Chen, Jingjia,Hu, Weipeng,Jin, Jing,Lovinger, Gabriel J.,Morken, James P.,Zhang, Chenlong
supporting information, p. 14189 - 14195 (2021/09/11)
In this paper is described a synthesis of enantiomerically enriched, configurationally stable organozinc reagents by catalytic enantioselective carbozincation of a vinylboronic ester. This process furnishes enantiomerically enriched α-borylzinc intermediates that are shown to undergo stereospecific reactions, producing enantioenriched secondary boronic ester products. The properties of the intermediate α-borylzinc reagent are probed and the synthetic utility of the products is demonstrated by application to the synthesis of (-)-aphanorphine and (-)-enterolactone.
Chiral Frustrated Lewis Pairs Catalyzed Highly Enantioselective Hydrosilylations of Ketones
Liu, Xiaoqin,Wang, Qiaotian,Han, Caifang,Feng, Xiangqing,Du, Haifeng
, p. 663 - 666 (2019/05/21)
A highly enantioselective Piers-type hydrosilylation of simple ketones was successfully realized using a chiral frustrated Lewis pair of tri-tert-butylphosphine and chiral diene-derived borane as catalyst. A wide range of optically active secondary alcohols were furnished in 80%—99% yields with 81%—97% ee's under mild reaction conditions.
One-pot synthesis of chiral alcohols from alkynes by CF3SO3H/ruthenium tandem catalysis
Liu, Huan,Liu, Sensheng,Zhou, Haifeng,Liu, Qixing,Wang, Chunqin
, p. 14829 - 14832 (2018/04/30)
A practical one-pot synthesis of chiral alcohols from readily available alkynes via tandem catalysis by the combination of CF3SO3H and a fluorinated chiral diamine Ru(ii) complex in aqueous CF3CH2OH is described. Very interestingly, the combination of fluorinated catalysts and solvent exhibits a positive fluorine effect on the reactivity and enantioselectivity. A range of chiral alcohols with wide functional group tolerance was obtained in high yield and excellent stereoselectivity under simple and mild conditions.
Expanding the Substrate Specificity of Thermoanaerobacter pseudoethanolicus Secondary Alcohol Dehydrogenase by a Dual Site Mutation
Musa, Musa M.,Bsharat, Odey,Karume, Ibrahim,Vieille, Claire,Takahashi, Masateru,Hamdan, Samir M.
, p. 798 - 805 (2018/02/21)
Here, we report the asymmetric reduction of selected phenyl-ring-containing ketones by various single- and dual-site mutants of Thermoanaerobacter pseudoethanolicus secondary alcohol dehydrogenase (TeSADH). The further expansion of the size of the substrate binding pocket in the mutant W110A/I86A not only allowed the accommodation of substrates of the single mutants W110A and I86A within the expanded active site but also expanded the substrate range of the enzyme to ketones bearing two sterically demanding groups (bulky–bulky ketones), which are not substrates for the TeSADH single mutants. We also report the regio- and enantioselective reduction of diketones with W110A/I86A TeSADH and single TeSADH mutants. The double mutant exhibited dual stereopreference to generate the Prelog products most of the time and the anti-Prelog products in a few cases.
Autoamplification-Enhanced Oxidative Kinetic Resolution of sec-Alcohols and Alkyl Mandelates, and its Kinetic Model
Talsi, Evgenii P.,Bryliakov, Konstantin P.
, p. 2693 - 2699 (2018/06/26)
In this contribution, the new dynamic nonlinear effect in asymmetric catalysis is discussed, manifesting itself in the oxidative kinetic resolution (OKR) of racemic secondary benzylic alcohols and alkyl mandelates with H2O2 in the presence of chiral Mn-based catalyst, with the apparent selectivity factor (krel) of the resolution being nonconstant over the reaction course. Typically, the initial growth of krel is changed into decay at high conversions. In this contribution, we demonstrate the oxidative kinetic resolution of various substrates bearing sec-alcoholic moieties, with the krel varying in different manners with increasing substrate conversion. We also present the predictive kinetic model of OKR with participation of asymmetric autoamplification. The influence of substrate and catalyst structure, as well as solvents and additives, on the behavior of krel variation, is discussed.
Nickel-Catalyzed Enantioconvergent Borylation of Racemic Secondary Benzylic Electrophiles
Wang, Zhaobin,Bachman, Shoshana,Dudnik, Alexander S.,Fu, Gregory C.
supporting information, p. 14529 - 14532 (2018/09/14)
Nickel-catalyzed cross-coupling has emerged as the most versatile approach to date for achieving enantioconvergent carbon–carbon bond formation using racemic alkyl halides as electrophiles. In contrast, there have not yet been reports of the application of chiral nickel catalysts to the corresponding reactions with heteroatom nucleophiles to produce carbon–heteroatom bonds with good enantioselectivity. Herein, we establish that a chiral nickel/pybox catalyst can borylate racemic secondary benzylic chlorides to provide enantioenriched benzylic boronic esters, a highly useful family of compounds in organic synthesis. The method displays good functional group compatibility (e.g., being unimpeded by the presence of an indole, a ketone, a tertiary amine, or an unactivated alkyl bromide), and both of the catalyst components (NiCl2?glyme and the pybox ligand) are commercially available.
Enantioselective 1,2-Anionotropic Rearrangement of Acylsilane through a Bisguanidinium Silicate Ion Pair
Cao, Weidi,Tan, Davin,Lee, Richmond,Tan, Choon-Hong
, p. 1952 - 1955 (2018/02/17)
Highly enantioselective bisguanidinium-catalyzed tandem rearrangements of acylsilanes are reported. The acylsilanes were activated via an addition of fluoride on the silicon to form a penta-coordinate anionic silicate intermediate. The silicate then underwent alkyl or aryl group migration from the silicon atom to the neighboring carbonyl carbon atom (1,2-anionotropic rearrangement), followed by [1,2]-Brook rearrangement to provide the secondary alcohols in high yields with excellent enantioselectivities (up to 95% ee). The isolation of an α-silylcarbinol intermediate as well as DFT calculations revealed that the 1,2-anionotropic rearrangement occurred via a bisguanidinium silicate ion pair, which is the stereodetermining step. The chiral center formed is then retained without inversion through the subsequent [1,2]-Brook rearrangement. Crotyl acylsilanes were smoothly transformed into homoallylic linear crotyl alcohols with retention of E/Z geometry, and no branched alcohols were detected. This clearly suggested that the 1,2-anionotropic rearrangement occurred through a three-membered instead of a five-membered transition state.
Catalytic conjunctive cross-coupling enabled by metal-induced metallate rearrangement
Zhang, Liang,Lovinger, Gabriel J.,Edelstein, Emma K.,Szymaniak, Adam A.,Chierchia, Matteo P.,Morken, James P.
, p. 70 - 74 (2016/01/09)
Transition metal catalysis plays a central role in contemporary organic synthesis. Considering the tremendously broad array of transition metal-catalyzed transformations, it is remarkable that the underlying elementary reaction steps are relatively few in
Cobalt-catalyzed asymmetric hydroboration of aryl ketones with pinacolborane
Guo, Jun,Chen, Jianhui,Lu, Zhan
supporting information, p. 5725 - 5727 (2015/03/30)
The highly enantioselective cobalt-catalyzed hydroboration reaction of aryl ketones with HBpin was developed using iminopyridine oxazoline ligands. Halides, amines, ethers, sulfides, esters and amides are well tolerated under the mild reaction conditions, demonstrating its synthetic advantage. Substituted diaryl ketones could also be hydroborated with high enantioselectivity.
