824938-98-9Relevant articles and documents
Asymmetric cycloetherification of in situ generated cyanohydrins through the concomitant construction of three chiral carbon centers
Kurimoto, Yosuke,Nasu, Teruhisa,Fujii, Yuki,Asano, Keisuke,Matsubara, Seijiro
, p. 2156 - 2160 (2019/03/26)
The organocatalytic enantio- A nd diastereoselective cycloetherification of in situ generated cyanohydrins through the concomitant construction of three chiral carbon centers is reported. This protocol facilitates the concise synthesis of optically active
Kinetic Resolution of Acylsilane Cyanohydrins via Organocatalytic Cycloetherification
Matsumoto, Akira,Asano, Keisuke,Matsubara, Seijiro
supporting information, p. 116 - 120 (2018/12/05)
An asymmetric cyanation of acylsilanes involving the in-situ formation of chiral acylsilane cyanohydrins followed by their kinetic resolution via organocatalytic cycloetherification is described. The highly enantio- and diastereoselective cycloetherificat
Organocatalytic Enantio- and Diastereoselective Construction of syn-1,3-Diol Motifs via Dynamic Kinetic Resolution of in Situ Generated Chiral Cyanohydrins
Matsumoto, Akira,Asano, Keisuke,Matsubara, Seijiro
supporting information, p. 2688 - 2692 (2019/04/30)
An organocatalytic method for the asymmetric synthesis of syn-1,3-dioxanes as protected 1,3-diols via dynamic kinetic resolution of in situ generated chiral cyanohydrins has been developed. This method involves a reversible cyanohydrin formation/hemiaceta
Squaramide-Linked Chloramphenicol Base Hybrid Catalysts for the Asymmetric Michael Addition of 2,3-Dihydrobenzofuran-2-carboxylates to Nitroolefins
Yan, Linjie,Huang, Guanxin,Wang, Haifeng,Xiong, Fangjun,Peng, Haihui,Chen, Fener
supporting information, p. 99 - 103 (2018/01/17)
An array of hybrid catalysts incorporating a chloramphenicol base moiety linked to another chiral scaffold through a squaramide linker were developed and successfully used in the Michael addition of 2,3-dihydrobenzofuran-2-carboxylates to nitroolefins. Control experiments suggested that the hybrid catalysts were more reactive than nonhybridized bifunctional catalysts, and matching of the chirality between the two scaffolds was crucial for high reactivity and stereoselectivity. These hybrid organocatalysts could be used with a variety of substrates. At a 0.5 mol-% catalyst loading, a range of 2,3-dihydrobenzofuran-2-carboxylates derivatives bearing quaternary and tertiary stereogenic centers were obtained in high yields (up to 98 %) with excellent enantioselectivities (up to 99 % ee) and moderate diastereoselectivities (up to 8:92 dr).
Investigations towards the stereoselective organocatalyzed Michael addition of dimethyl malonate to a racemic nitroalkene: Possible route to the 4-methylpregabalin core structure
Vargová, Denisa,Baran, Rastislav,?ebesta, Radovan
, p. 553 - 559 (2018/03/21)
Chiral derivatives of γ-aminobutyric acid are widely used as medicines and can be obtained by organocatalytic Michael additions. We show here the stereoselective synthesis of 4-methylpregabalin stereoisomers using a Michael addition of dimethyl malonate to a racemic nitroalkene. The key step of the synthesis operates as a kinetic resolution with a chiral squaramide catalyst. Furthermore, specific organocatalysts can provide respective stereoisomers of the key Michael adduct in up to 99:1 er.
Trans -1,2-Diaminocyclohexane-based sulfonamides as effective hydrogen-bonding organocatalysts for asymmetric Michael-hemiacetalization reaction
Dajek, Maciej,Kowalczyk, Rafa?,Boratyński, Przemys?aw J.
, p. 4358 - 4363 (2018/09/11)
An easily attainable bifunctional monosulfonamide derivative of DACH was an effective catalyst for Michael addition-hemiacetalization reactions, providing products with ees exceeding 99% under optimized conditions. High enantioselectivities were achieved with just 0.2% mol catalyst loading. The sulfonamide outperformed analogous thiourea and squaramide-based organocatalysts.
Kinetic Resolution of 5-Substituted Oxazinones with Bifunctional Chiral Base/Squaramide Organocatalysts
Er?ksüz, Serap,Neud?rfl, J?rg M.,Berkessel, Albrecht
, p. 1278 - 1281 (2017/06/27)
5-Substituted oxazinones provide N-protected β 2 -amino acid esters upon alcoholytic ring opening. Thus far, this access to enantiopure β 2 -amino acids has been restricted to the use of enzymes (hydrolases) as catalysts for the kine
Development of Chiral, Bifunctional Thiosquaramides: Enantioselective Michael Additions of Barbituric Acids to Nitroalkenes
Rombola, Michael,Sumaria, Chintan S.,Montgomery, Thomas D.,Rawal, Viresh H.
, p. 5297 - 5300 (2017/04/27)
We report a general method for the synthesis of chiral thiosquaramides, a class of bifunctional catalysts not previously described in the literature. Thiosquaramides are found to be more acidic and significantly more soluble in nonpolar solvents than their oxosquaramide counterparts, and they are excellent catalysts for the unreported, enantioselective conjugate addition reaction of the barbituric acid pharmacaphore to nitroalkenes, delivering the chiral barbiturate derivatives in high yields and high enantioselectivities, even with catalyst loadings as low as 0.05 mol%.
Organocatalytic Enantioselective Vinylogous Aldol Reaction of Allyl Aryl Ketones to Activated Acyclic Ketones
Jing, Zhenzhong,Bai, Xiangbin,Chen, Wenchao,Zhang, Gao,Zhu, Bo,Jiang, Zhiyong
supporting information, p. 260 - 263 (2016/02/03)
The first catalytic asymmetric vinylogous aldol reaction of activated allyls to activated acyclic ketones is disclosed. A variety of activated acyclic ketones, such as trifluoromethyl ketones, α-ketoesters, and α-keto phosphonates, were found to be involved forming diverse γ-selective aldol adducts with high enantioselectivities (up to >99% ee). The method provides an effective, general strategy to access valuable chiral electron-withdrawing group-substituted tertiary hydroxyl-based carboxylic acids.
Enantioselective Mannich reaction of β-keto esters with aromatic and aliphatic imines using a cooperatively assisted bifunctional catalyst
Neuvonen, Antti J.,Pihko, Petri M.
supporting information, p. 5152 - 5155 (2015/01/08)
An efficient urea-enhanced thiourea catalyst enables the enantioselective Mannich reaction between β-keto esters and N-Boc-protected imines under mild conditions and minimal catalyst loading (1-3 mol %). Aliphatic and aromatic substituents are tolerated on both reaction partners, affording the products in good enantiomeric purity. The corresponding β-amino ketones can readily be accessed via decarboxylation without loss of enantiomeric purity.
