- 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
-
A particularly general protocol for the organocatalytic asymmetric Michael addition of nitroalkanes to α,β-unsaturated enones is reported. The Michael reaction proceeded smoothly and provided the desired adducts in moderate to excellent yields (55–99%) an
- Liu, Siyang,Wang, Qingqing,Ye, Ling,Shi, Zhichuan,Zhao, Zhigang,Yang, Xuejun,Ding, Keyi,Li, Xuefeng
-
supporting information
p. 5115 - 5120
(2016/07/25)
-
- Kinetic resolution of aminoalkenes by asymmetric hydroamination: A mechanistic study
-
The kinetic resolution of chiral aminoalkenes by hydroamination-cyclization was studied by using 3,3'-bis(triarylsilyl)-substituted binaphtholate rare-earth-metal complexes. The resolution of 1-arylaminopentenes proceeds with high efficiency and high irans-diastereoselectivity, whereas the resolution process of 1-alkylaminopentenes suffers from decreasing resolution efficiency with increasing steric demand of the aliphatic substituent. Kinetic studies of the matching and mismatching substrate-catalyst pair by using enantiopure substrates and either the (R)- or (S)-binaphtholate catalysts revealed that the difference in resolution efficiency stems from a shift of the Curtin-Hammett pre-equilibrium. Al-though 1-arylaminopentenes favor the matching substrate-catalyst complex, preference for the mismatching substrate-catalyst complex for 1-alkylaminopentenes diminishes resolution efficiency. Nevertheless, the relative cyclization rate for the two diastereomeric substrate-catalyst complexes remains in a typical range of 7-10:1. Plausible attractive π interactions between the aryl substituent and either the metal center or the aromatic system of the bis(triarylsilyl)-substituted binaphtholate ligand may explain increased sta-bility of the matching substrate-catalyst complex. Incidentally, the methoxymethyl (MOM)-substituted aminopentene 3g also exhibited a strong preference for the matching substrate-catalyst complex, possibly due to the chelating nature of the MOM substituent. The proximity of the stereocenter to the amino group in the aminoalkene substrate was crucial to achieve good kinetic resolution efficiency. The more remote β-phenyl substituent in 2-phenylpent-4-en-l-amine (5) resulted in diminished discrimination of the substrate enantiomers with respect to the relative rate of cyclization of the two substrate-catalyst complexes and a Curtin-Hammett preequilibrium close to unity.
- Reznichenko, Alexander L.,Hampel, Frank,Hultzsch, Kai C.
-
scheme or table
p. 12819 - 12827
(2010/06/17)
-
- HETEROCYCLIC ARYLSULPHONES SUITABLE FOR TREATING DISORDERS THAT RESPOND TO MODULATION OF THE SEROTONIN 5HT6 RECEPTOR
-
The invention relates to compounds of the formula (I) wherein the variables have meanings given in the claims and the description. The invention also relates to the use of a compound of the formula (I) or a pharmaceutically acceptable salt thereof for pre
- -
-
-