An easy route to exotic 9-epimers of 9-amino-(9-deoxy) cinchona alkaloids with (8S, 9R) and (8R, 9S)-configurations through two inversions of configuration
摘要:
Four exotic chiral organocatalysts, 9-amino-(9-deoxy) cinchona alkaloids with (8S, 9R) and (8R, 9S)-configurations, were conveniently synthesized for the first time in 27-72% total yields through two conversions of configuration at the 9-stereogenic centers of commercially available cinchona alkaloids. (C) 2013 Xue-Bing Ma and Ming Li. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
An easy route to exotic 9-epimers of 9-amino-(9-deoxy) cinchona alkaloids with (8S, 9R) and (8R, 9S)-configurations through two inversions of configuration
摘要:
Four exotic chiral organocatalysts, 9-amino-(9-deoxy) cinchona alkaloids with (8S, 9R) and (8R, 9S)-configurations, were conveniently synthesized for the first time in 27-72% total yields through two conversions of configuration at the 9-stereogenic centers of commercially available cinchona alkaloids. (C) 2013 Xue-Bing Ma and Ming Li. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
The synthesis of novel, highly functionalized, C 2-symmetric sulfur-based catalysts is developed and their catalytic applications are explored in asymmetric bromo-, iodo- and seleno-functionalizations of alkenoicacids. This protocol provides the corresponding normal- and medium-sized bromo, iodo and selenolactones in up to 98% yield and 83% stereoselectivity.
开发了新型、高度官能化的 C 2 对称硫基催化剂的合成,并探索了它们在烯酸的不对称溴、碘和硒官能化中的催化应用。该方案以高达 98% 的产率和 83% 的立体选择性提供相应的正常和中等大小的溴、碘和硒内酯。
An eccentric rod-like linear connection of two heterocycles: synthesis of pyridine <i>trans</i>-tetrafluoro-λ<sup>6</sup>-sulfanyl triazoles
The trans-tetrafluoro-λ6-sulfane (SF4) group has been utilized as a unique three-dimensional building block for the linear connection of two independent N-heterocycles, pyridines and triazoles. The linearly connected heterocycliccompounds were synthesized by thermal Huisgen 1,3-dipolar cycloaddition between previously unknown pyridine SF4-alkynes and readily available azides, providing a series of
Cinchona alkaloid derivatives featuring a guanidinium group in diverse positions efficiently catalyze the cleavage of the RNA model compound 2-hydroxypropyl p-nitrophenyl phosphate (HPNP). Their high catalytic efficiency as phosphodiesterases and the potentiometric and kinetic investigations indicate the existence of a high degree of cooperation between the guanidinium group and the quinuclidine moiety
A series of Cinchona alkaloid-derived dimers were obtained in high yields in copper-catalyzed 1,3-dipolar “click” cycloaddition using bis(TMS)butadiyne and other bivalent alkynes. The products with bitriazole linkers were effective ligands for asymmetric copper-catalyzed Michael addition. It was shown that the presence of such linker was responsible for effective chirality transfer.
The production of chiral pyrrolodiketopiperazines under organocatalytic conditions demonstrates the capacity of bicyclic acylpyrrol lactims to perform as pronucleophiles in direct carbon–carbon bond forming reactions. The good performance of ureidoaminal-derived Brønsted bases in the Michael addition to nitroolefins affords these heterocyclic scaffolds with high skeleton diversity.