22440-34-2Relevant academic research and scientific papers
Lewis Acid Assisted Electrophilic Fluorine-Catalyzed Pinacol Rearrangement of Hydrobenzoin Substrates: One-Pot Synthesis of (±)-Latifine and (±)-Cherylline
Shi, Hui,Du, Chuan,Zhang, Xinhang,Xie, Fukai,Wang, Xiaoyu,Cui, Shanshan,Peng, Xiaoshi,Cheng, Maosheng,Lin, Bin,Liu, Yongxiang
, p. 1312 - 1319 (2018/02/09)
A microwave-irradiated solvent-free pinacol rearrangement of hydrobenzoin substrates catalyzed by a combination of N-fluorobenzenesulfonimide and FeCl3·6H2O was developed. Its selectivity was first investigated by density functional theory (DFT) calculations. Then the functional group tolerance was examined by synthesizing a series of substrates designed based on the insight provided by the DFT calculations. The application of the methodology was demonstrated by the efficient one-pot synthesis of (±)-latifine and (±)-cherylline, both are 4-aryltetrahydroisoquinoline alkaloids isolated from Amaryllidacecae plants.
Cyclodextrin ketones with the catalytic group at the secondary rim and their effectiveness in enzyme-like epoxidation of stilbenes
Fenger, Thomas Hauch,Marinescu, Lavinia G.,Bols, Mikael
scheme or table, p. 2339 - 2345 (2011/06/20)
Several new cyclodextrin ketones with a ketone attached to the secondary face of the cyclodextrin in the form of a 2,3-O-(2-oxopropane-1,3-diyl) or 2-oxo group are reported. These compounds and a selection of known cyclodextrin ketones having the ketone at the primary face were investigated as epoxidation catalysts for oxidation of stilbenes and styrene. A method for determination of kcat in these epoxidations is presented, which was used to determine the rate accelerations for the cyclodextrin ketones relative to background reaction. The highest rate acceleration obtained for epoxidation of 4-methoxy-4′-nitro-trans-stilbene was 221. The highest enantioselectivity obtained was 76% ee of (S)-styrene oxide. A cyclodextrin bearing a ketone on the secondary face can catalyze the epoxidation of stilbenes with cavity induced rate increases of 100-200 and stereoselectivity. Copyright
Experimental evidence for multiple oxidation pathways in the (salen)Mn-catalyzed epoxidation of alkenes
Linde, Christian,Koliai, Nordine,Norrby, Per-Ola,Akermark, Bjoern
, p. 2568 - 2573 (2007/10/03)
The substrate electronic effects on the selectivity in the catalytic epoxidation of para-substituted cis stilbenes 2a-i were investigated by using (R,R)-[N,N′-bis(3,5-di-tBu-salicylidene)-1,2-cyclohexanediamine] manganese(III) chloride 1 in benzene as the catalyst with iodosobenzene as the terminal oxidant. A Hammett study of the selectivity results reveals a stronger electrophilic character than previously assumed in the (salen)Mn-catalyzed reaction. In general, the best correlations with the experimental values were obtained by using the Hammett σ+ values, which gave ρ = -1.37 for the rate of cisepoxide formation and ρ = -0.43 for the rate of the stepwise process leading to the corresponding trans product. The reaction involves two separate pathways as indicated also by the competitive breakdown of the intermediate on the path to trans epoxide for methoxy-substituted substrates. The asynchronicity in the concerted pathway leading to cis epoxide is apparent for 4-methoxy-4′-nitrostilbene, which yields cis epoxide with 75% ee entirely as a result of electronic effects.
