4-Fluoro and 4-Hydroxy Pyrrolidine-thioxotetrahydropyrimidinones: Organocatalysts for Green Asymmetric Transformations in Brine
作者:Nikolaos Kaplaneris、Giorgos Koutoulogenis、Marianna Raftopoulou、Christoforos G. Kokotos
DOI:10.1021/acs.joc.5b00283
日期:2015.6.5
The synthesis of both trans- and cis-diastereomers of pyrrolidinine-thioxotetrahydropyrimidinone bearing either a fluorine or a hydroxyl group was accomplished. The new compounds were tested for their catalytic properties in a variety of asymmetric organic transformations and compared with the first generation catalyst. It was found that the new catalysts could efficiently catalyze the reactions in
Chiral anthranilic pyrrolidine as custom-made amine catalyst for enantioselective Michael reaction of nitroalkenes with carbonyl compounds
作者:Yukari Oka、Seiji Tsuzuki、Katsuhiko Moriyama
DOI:10.1039/d1cc04453b
日期:——
pyrrolidine catalyst as a custom-made amine-catalyst was developed for the enantio- and diastereo selective Michael reaction of nitroalkenes with carbonylcompounds. In particular, a peptide-like catalyst in which an α-amino acid is attached to the anthranilic acid skeleton induced the high stereoselectivity of the reaction with aldehydes. Studies of the reaction mechanism indicated that the catalyst exhibits
A novel type of pyrrolidine-based chiral (thio)phosphoramidates was synthesized. Among them, compound (S,aR)-3d was proven to be an effective bifunctional organocatalyst for the asymmetric Michaeladdition of ketones to nitroolefins. The corresponding adducts were obtained in good to excellent chemical yields with high levels of diastereo- and enantioselectivities (up to >99:1 dr and 99 % ee).
合成了一种新型的基于吡咯烷的手性(硫代)氨基磷酸酯。其中,化合物 (S,aR)-3d 被证明是一种有效的双功能有机催化剂,用于酮与硝基烯烃的不对称迈克尔加成。相应的加合物以良好到优异的化学产率获得,具有高水平的非对映选择性和对映选择性(高达 >99:1 dr 和 99% ee)。
Asymmetric Michael addition catalysed by sugar-based prolinamides in solvent-free conditions
作者:Jyoti Agarwal、Rama Krishna Peddinti
DOI:10.1016/j.tetlet.2010.10.148
日期:2011.1
Sugar-based prolinamides derived from glucosamine have been developed as organocatalysts for the asymmetric Michael addition between cyclohexanones and nitroolefins. Numerous polar and nonpolar solvents and additives have been screened in the current study. The organocatalyst 1c in the presence of benzoic acid as additive catalysed the reaction under neat conditions to afford Michael adducts in high
The direct smallpeptide-catalyzedenantioselective Michael addition of ketones to nitroolefins is presented. Simple di- and tripeptides derived from alanine catalyze the asymmetric Michael additions with high stereoselectivity and furnish the corresponding Michael products in high yield with up to 68 : 1 dr and 98% ee. The study demonstrates that small, readily prepared peptides with increased structural