22418-65-1Relevant articles and documents
The cinchona primary amine-catalyzed asymmetric epoxidation and hydroperoxidation of α,β-unsaturated carbonyl compounds with hydrogen peroxide
Lifchits, Olga,Mahlau, Manuel,Reisinger, Corinna M.,Lee, Anna,Fares, Christophe,Polyak, Iakov,Gopakumar, Gopinadhanpillai,Thiel, Walter,List, Benjamin
supporting information, p. 6677 - 6693 (2013/06/05)
Using cinchona alkaloid-derived primary amines as catalysts and aqueous hydrogen peroxide as the oxidant, we have developed highly enantioselective Weitz-Scheffer-type epoxidation and hydroperoxidation reactions of α,β-unsaturated carbonyl compounds (up to 99.5:0.5 er). In this article, we present our full studies on this family of reactions, employing acyclic enones, 5-15-membered cyclic enones, and α-branched enals as substrates. In addition to an expanded scope, synthetic applications of the products are presented. We also report detailed mechanistic investigations of the catalytic intermediates, structure-activity relationships of the cinchona amine catalyst, and rationalization of the absolute stereoselectivity by NMR spectroscopic studies and DFT calculations.
N-heterocyclic carbene catalyzed umpolung of Michael acceptors for intermolecular reactions
Biju, Akkattu T.,Padmanaban, Mohan,Wurz, Nathalie E.,Glorius, Frank
supporting information; experimental part, p. 8412 - 8415 (2011/10/31)
leahciM! The N-heterocyclic carbene catalyzed umpolung of Michael acceptors proceeds through the formation of a deoxy-Breslow intermediate (see scheme; EWG=electron-withdrawing group). This nucleophilic species can react with other Michael acceptors in an intermolecular fashion, thereby resulting in the formation of homo- or heterodimeric olefins. This "Michael umpolung" should become a valuable method for the formation of densely functionalized olefins.
Diastereoselective addition of organozinc reagents to 2-alkyl-3- (arylsulfanyl)propanals
Larsson, Michael,Galandrin, Elodie,H?gberg, Hans-Erik
, p. 10659 - 10669 (2007/10/03)
The preparation of compounds incorporating the 3-hydroxy-2-methyl-1-alkyl moiety of high diastereomeric purity is described. Such compounds can serve as potential building blocks for the preparation of several kinds of natural products. Diastereoselective synthesis of two potential pine sawfly pheromone components, one the pure racemic threo-isomer of 3-methylpentadecan-2-ol and the other the racemic erythro-isomer of 3-methyltridecan-2-ol are described. The diastereoselective addition of R2Zn (R=Me, Et and n-Bu) to several 2-alkyl-3-(arylsulfanyl)propanals in the presence of a Lewis acid and CH 2Cl2 as solvent was studied. An excellent diastereomeric ratio (95/5 anti-Cram/Cram) was obtained with 2-[(phenylsulfanyl)methyl] pentanal, 2-[(phenylsulfanyl)methyl]decanal and 2-[(phenylsulfanyl)methyl] dodecanal and Me2Zn in the presence of TiCl4. (a) Lewis acid catalysed dimethylzinc addition; (b) 1. Prot. and oxidation to sulfone, 2. Alkylation; (c) Deprot. and desulfonation; (d) Desulfurisation.
Molecular Design of the Electron-Donating Sidearm of Lariat Ethers: Effective Coordination of the Quinoline Moiety in Complexation toward Alcali-Metal Cations
Nakatsuji, Yohji,Nakamura, Tetsuya,Yonetani, Masayuki,Yuya, Hajime,Okahara, Mitsuo
, p. 531 - 538 (2007/10/02)
The electron-donating sidearm of alkyl-substituted lariat ethers based on 15-crown-5, 16-crown-5, and 18-crown-6 was modified to clarify the contribution to the complexation of the sidearm toward alkali-metal cations.A specific coordination property of the quinoline sidearm was shown by measuring the complexing ability in methanol at 25 deg C, the change of the chemical shift in the 1H NMR spectrum, a characreristic absorption in the UV spectrum, the exrtactability, and the transport ability.The methyl-substituted lariat ether based on 15-crown-5 or 18-crown-6 displayed an excellent selectivity toward Na+ or K+, resoectively, comparedwith the unsubstituted ethers.
