1104643-40-4Relevant academic research and scientific papers
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
supporting information, 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.
Mechanistic consideration of asymmetric CN and CC bond formations with bifunctional chiral ir and ru catalysts
Hasegawa, Yasuharu,Gridnev, Ilya D.,Ikariya, Takao
supporting information; experimental part, p. 316 - 334 (2012/05/07)
The mechanism of two enantioselective reactions, direct amination of α-cyanoacetates 3 with azodicarboxylates 4 and CC bond formation reaction of α-cyanoacetates with acetylenic esters 6, catalyzed by chiral bifunctional Ir and Ru complexes, Cp*Ir[(S,S)-N
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.
Di-tert-butyl dicarbonate: a versatile carboxylating reagent
Augustine, John Kallikat,Arthoba Naik,Vairaperumal, Veeramani,Narasimhan, Sharmila
experimental part, p. 134 - 138 (2009/04/06)
Carbon nucleophiles generated by a non-nucleophilic base (LDA) were effectively trapped with di-tert-butyl dicarbonate (Boc-anhydride) to provide the corresponding tert-butyl aryl acetates, di-tert-butyl aryl malonates, unsymmetrical aryl malonates and te
Enantioselective bimetallic catalysis of michael additions forming quaternary stereocenters
Jautze, Sascha,Peters, Rene
supporting information; experimental part, p. 9284 - 9288 (2009/05/15)
Robotlike: Low catalyst loadings of a planar-chiral ferrocenyl bispalladacycle are sufficient to catalyze the Michael addition of trisubstituted α-cyanoacetates to enones with excellent yields (TONs up to 2450) and high enantioselectivity. The reaction proceeds by a cooperative bimetallic mechanism and is superior to previous methods relying on soft Lewis acid catalysts. (Chemical Equation Presented)
