Iterative Coupling of Two Different Enones by Nitromethane Using Bifunctional Thiourea Organocatalysts. Stereocontrolled Assembly of Cyclic and Acyclic Structures
摘要:
An organocatalytic iterative assembly line has been developed in which nitromethane was sequentially coupled with two different enones using a combination of pseudoenantiomeric cinchona-based thiourea catalysts. Application of unsaturated aldehydes and ketones in the second step of the iterative sequence allows the construction of cyclic synketols and acyclic compounds with multiple contiguous stereocenters. The combination of the multifunctional substrates and ambident electrophiles rendered some organocatalytic transformations possible that have not yet been realized in bifunctional noncovalent organocatalysis.
Enantioselective Conjugate Addition of Both Aromatic Ketones and Acetone to Nitroolefins Catalyzed by Chiral Primary Amines Bearing Multiple Hydrogen-Bonding Donors
of chiral primary amine catalysts bearing multiple hydrogen-bonding donors have been designed and synthesized. The newly developed bifunctional organocatalysts efficiently catalyzed not only enantioselectiveconjugateaddition of aromatic ketones to nitroolefins in good yields (up to 87%) with excellent enantioselectivities (97→99% ee) but also enantioselectiveconjugateaddition of acetone to nitroolefins
A general, highly enantioselective Michael addition of nitroalkanes to α,β-unsaturated enones catalyzed by 9-amino(9-deoxy)-epi-quinine: a remarkable additive effect
作者:Siyang Liu、Qingqing Wang、Ling Ye、Zhichuan Shi、Zhigang Zhao、Xuejun Yang、Keyi Ding、Xuefeng Li
DOI:10.1016/j.tet.2016.07.008
日期:2016.8
A particularly general protocol for the organocatalytic asymmetric Michael addition of nitroalkanes to α,β-unsaturated enones is reported. The Michaelreaction proceeded smoothly and provided the desired adducts in moderate to excellent yields (55–99%) and good to excellent enantioselectivities (65–99% ee). The addition of readily available achiral base significantly enhanced the reactivity without
Enantioselective Synthesis of Chiral Propargylic Alcohols Catalyzed by Bifunctional Zinc-Based Complexes
作者:Xinhua Lu、Guanlei Xie、Tingyi Li、Xiaoming Qu、Jincheng Mao
DOI:10.1080/00397911.2010.531367
日期:2012.3.15
Abstract This work demonstrates an efficient way to prepare chiral propargylicalcohols by asymmetric addition of terminal Zn-acetylide to aldehydes catalyzed by bifunctional zinc-based complexes. The corresponding products with moderate to good yields and enantioselectivities were obtained in the absence of moisture-sensitive Ti(O i Pr)4. GRAPHICAL ABSTRACT
摘要 这项工作展示了一种通过将末端 Zn-乙炔化物不对称加成到由双功能锌基配合物催化的醛类制备手性炔丙醇的有效方法。在不存在对水分敏感的 Ti(O i Pr) 4 的情况下,获得了具有中等至良好产率和对映选择性的相应产品。图形概要
Highly Enantioselective Michael Addition of Nitroalkanes to Chalcones Using Chiral Squaramides as Hydrogen Bonding Organocatalysts
作者:Wen Yang、Da-Ming Du
DOI:10.1021/ol102294g
日期:2010.12.3
squaramide-based organocatalysts were facilely synthesized and applied as hydrogen bonding organocatalysts in the enantioselectiveMichaeladdition of nitroalkanes to chalcones. These organocatalysts promoted the Michaeladdition with low catalyst loading under high temperature (80 °C), affording the desired R or S enantiomers of the products flexibly in high yields with excellent enantioselectivities (93−96%
Asymmetric Michael Addition of Aromatic Ketones to Nitroolefins Catalyzed by Simple Chiral Bifunctional Primary Amine-Thioureas
作者:Liangliang Wang、Xiaoying Xu、Jun Huang、Lin Peng、Qingchun Huang、Lixin Wang
DOI:10.2174/157017810791514652
日期:2010.7.1
Simple chiral primary amine-thiourea catalysts derived from chiral 1,2-diphenylethylenediamine were found to catalyze direct Michael addition of aromatic ketones to nitroolefins with good enantioselectives (up to 86% ee) and excellent yields (up to 97%) for a broad range of substrates and successfully used in the preparation of (R)-Balcofen.