由手性膦BINAP容易制备的手性膦氧化物BINAPO在三氯甲硅烷基化合物通过高价硅酸盐中间体的反应中表现出良好的催化活性。在催化量的BINAPO存在下,醛与烯丙基三氯硅烷的烯丙基化反应使烯丙基化的加合物具有良好的对映选择性(最高79%ee),其中二异丙基乙胺和四丁基碘化铵作为添加剂的组合对于加速催化循环至关重要。31氧化膦的1 P NMR分析表明,胺促进了氧化膦从硅原子上的解离。BINAPO还促进了二异丙基乙胺作为添加剂存在下醛与三氯甲硅烷基烯醇醚的对映体选择性醛醇缩合反应,从而以高非对映体和对映体选择性(最高syn / anti = 1 / 25,96%ee(anti))提供了相应的醛醇加合物。)。
Prolinamides of Aminouracils, Organocatalyst Modifiable by Complementary Modules
作者:Karen M. Ruíz-Pérez、Beatriz Quiroz-García、Marcos Hernández-Rodríguez
DOI:10.1002/ejoc.201800886
日期:2018.11.8
Prolinamide organocatalysts with aminouracils have the features of enhanced NH acidity, an additional hydrogen‐bond donor and the self‐assembly with complementary modules by Watson–Crick pairing. Each module affects the selectivity of the reaction and particularly 2,6‐diaminopyridine is beneficial to the selectivity in the reaction.
[reaction: see text] Readily tunable and bifunctional L-prolinamides as novel organocatalysts have been developed, and their catalytic activities were evaluated in the direct asymmetric Aldolreactions of various aromatic aldehydes and cyclohexanone. High isolated yields (up to 94%), enantioselectivities (up to 99% ee), and anti-diastereoselectivities (up to 99:1) were obtained under the optimal conditions
Highly efficient organocatalysts for the asymmetric aldol reaction
作者:C. G. Jacoby、P. H. V. Vontobel、M. F. Bach、P. H. Schneider
DOI:10.1039/c7nj04424k
日期:——
synthetic route. The highly efficient five step methodology did not require intermediary purification and provided the compounds in high yields. The catalysts were successfully applied in the asymmetric direct aldolreaction between aromatic aldehydes and cyclic ketones in aqueous media. Aldol adducts were obtained in high yields with perfect stereoselectivities (up to >99% e.e. and >19 : 1 d.r.).
3,3′-Bithiophene-Based Chiral Bisphosphine Oxides as Organocatalysts in Silicon-Derived Lewis Acid Mediated Reactions
作者:Sergio Rossi、Tiziana Benincori、Laura Maria Raimondi、Maurizio Benaglia
DOI:10.1055/s-0039-1690777
日期:2020.4
This account summarizes the development of new biheteroaromatic chiral bisphosphine oxides. 3,3′-Bithiophene-based phosphine oxides (BITIOPOs) have been successfully used as organocatalysts to promote Lewis base catalyzed, Lewis acid mediated stereoselective transformations. These highly electron-rich compounds, in combination with trichorosilyl derivatives (allyltrichlorosilane and silicon tetrachloride)
Design and preparation of a novel prolinamide-based organocatalyst for the solvent-free asymmetric aldol reaction
作者:Rafaela de S. Martins、Mathias P. Pereira、Pedro P. de Castro、Fernanda I. Bombonato
DOI:10.1016/j.tet.2019.130855
日期:2020.1
proline-derived catalyst, providing access to the desired adducts in up to 95% yield, 1:19 syn/anti and 98% e.e. Moreover, even sterically bulky aldehydes and substituted cyclohexanones were well tolerated. DFT calculations and control experiments indicated that several hydrogen bonding interactions between the aldehyde and the enamine intermediate are responsible for the stereoselective chiral induction process