Chalk it up as a “Sc”andal: The asymmetricconjugateaddition of chalcone and “cinnamone” derivatives to nitromethane has been realized by using a simple and efficient scandium(III)–N,N′‐dioxide complex as the catalyst (see scheme). In the presence of 2–5 mol % catalyst loading, the corresponding products were formed in excellent yields (up to 99 %) and enantioselectivities (up to>99 % ee).
Six active 4-aryl-5-nitro-pentan-2-ones were synthesized enantioselectively from the corresponding 5-aryl-butenones by asymmetric Michael addition of nitromethane using an imidazolidine-type enantioselective organocatalyst. The ee ratio of the products were between 67 and 100%, determined by HPLC with Chiracel OD. Molecular and crystal structure of 3,4-methylenedioxy-phenyl-5-nitro-pentan-2-one has
Highly Efficient Amine Organocatalysts Based on Bispidine for the Asymmetric Michael Addition of Ketones to Nitroolefins
作者:Zhigang Yang、Jie Liu、Xiaohua Liu、Zhen Wang、Xiaoming Feng、Zhishan Su、Changwei Hu
DOI:10.1002/adsc.200800341
日期:2008.9.5
highly diastereoselective and enantioselective Michael addition of cyclohexanone, acetone and other ketones to nitroolefins was developed by the use of an amine organocatalyst based on bispidine. Additionally, a theoretical study of transition structures revealed that this bispidine-based primary-secondary amine catalyst could serve through an enamine intermediate and H-bond interaction, which was
A Bifunctional B,N‐Based Asymmetric Catalytic Nitrostyrene‐
<i>Michael</i>
Addition Acting through a 10‐Membered Ring Cyclic Transition State
作者:Yihao Du、Ozlem Sari、Safiye S. Erdem、Andrew Whiting
DOI:10.1002/hlca.202100199
日期:2021.12
The B,N-bifunctional catalyst homoboroproline has been applied to a catalytic asymmetric nitroalkene-Michael addition to β-nitrostyrene analogues, showing broad substrate tolerance, high conversions and moderate to good asymmetric induction. The ability of homoboroproline to act as an efficient catalyst based on enamine-formation of the secondary amine, coupled with intramolecular Lewis-acid chelation