923568-89-2Relevant articles and documents
Organocatalytic stereoselective conjugate addition of 3-substituted oxindoles with in situ generated ortho-quinone methides
Liang, Weihong,Yin, Wenhao,Wang, Tingzhong,Qiu, Fayang G.,Zhao, Junling
, p. 1742 - 1747 (2018/04/02)
A novel method for the stereoselective conjugate addition of 3-substituted oxindoles to in situ generated o-QMs was described. This process was catalyzed efficiently by a cinchonidine-derived squaramide catalyst in oil-water phase, furnishing the corresponding 3,3-disubsituted oxindole derivatives in moderate to high yields (up to 98%) with high stereoselectivities (up to 95% ee, 15.4:1 dr). The utility of this reaction was also investigated by the gram-scale synthesis and derivatization of one of the products.
Enantioselective construction of tetrasubstituted stereogenic carbons through bronsted base catalyzed michael reactions: α′-hydroxy enones as key enoate equivalent
Badiola, Eider,Fiser, Bla,Gmez-Bengoa, Enrique,Mielgo, Antonia,Olaizola, Iurre,Urruzuno, Iaki,Garca, Jess M.,Odriozola, Jos M.,Razkin, Jess,Oiarbide, Mikel,Palomo, Claudio
, p. 17869 - 17881 (2015/02/19)
Catalytic and asymmetric Michael reactions constitute very powerful tools for the construction of new C-C bonds in synthesis, but most of the reports claiming high selectivity are limited to some specific combinations of nucleophile/electrophile compound types, and only few successful methods deal with the generation of all-carbon quaternary stereocenters. A contribution to solve this gap is presented here based on chiral bifunctional Bronsted base (BB) catalysis and the use of α′-oxy enones as enabling Michael acceptors with ambivalent H-bond acceptor/donor character, a yet unreported design element for bidentate enoate equivalents. It is found that the Michael addition of a range of enolizable carbonyl compounds that have previously demonstrated challenging (i.e., α-substituted 2-oxindoles, cyanoesters, oxazolones, thiazolones, and azlactones) to α′-oxy enones can afford the corresponding tetrasubstituted carbon stereocenters in high diastereo- and enantioselectivity in the presence of standard BB catalysts. Experiments show that the α′-oxy ketone moiety plays a key role in the above realizations, as parallel reactions under identical conditions but using the parent α,β-unsaturated ketones or esters instead proceed sluggish and/or with poor stereoselectivity. A series of trivial chemical manipulations of the ketol moiety in adducts can produce the corresponding carboxy, aldehyde, and ketone compounds under very mild conditions, giving access to a variety of enantioenriched densely functionalized building blocks containing a fully substituted carbon stereocenter. A computational investigation to rationalize the mode of substrate activation and the reaction stereochemistry is also provided, and the proposed models are compared with related systems in the literature.
Cinchona alkaloid catalyzed enantioselective fluorination of allyl silanes, silyl enol ethers, and oxindoles
Ishimaru, Takehisa,Shibata, Norio,Horikawa, Takao,Yasuda, Naomi,Nakamura, Shuichi,Toru, Takeshi,Shiro, Motoo
supporting information; experimental part, p. 4157 - 4161 (2009/03/11)
(Chemical Equation Presented) Catalytic variant: Allyl silanes and silyl enol ethers 1 are good substrates for the catalytic highly enantioselective fluorodesilylation using a combination of a biscinchona alkaloid, N-fluorobenzenesulfonimide (NFSI), and base (see scheme). Pharmaceutically attractive 3-aryl-3-fluorooxindoles such as 3 can also be synthesized with high enantioselectivity.
Lewis acid-catalyzed enantioselective hydroxylation reactions of oxindoles and β-keto esters using DBFOX ligand
Ishimaru, Takehisa,Shibata, Norio,Nagai, Jun,Nakamura, Shuichi,Toru, Takeshi,Kanemasa, Shuji
, p. 16488 - 16489 (2007/10/03)
The first catalytic enantioselective hydroxylation reaction of both 3-aryl and 3-alkyl-2-oxindoles using the DBFOX-Zn(II) complex, leading to pharmaceutically important chiral 3-hydroxy-2-oxindoles was described. The structure of oxidant was found to play
