92851-01-9Relevant academic research and scientific papers
Insights into the diastereoselective control in the sulfa-Michael addition of thiols to nitroalkenes: Stereoelectronic effect in the cyclic chelated transition state
Wang, Jiandong,Li, Pingfan,Yang, Zhanhui,Chen, Ning,Xu, Jiaxi
, p. 370 - 378 (2016)
The diastereoselective control in the sulfa-Michael addition of nitroalkenes and lithium thiolates followed by protonation was investigated. Lithium thiolates first added to nitroalkenes to afford cyclic lithium-chelated nitronates. The subsequent kinetic protonation of nitronates was proved to be the stereochemical determinant through the chelate-controlled six-membered half-chair transition state bearing two approximately 1,2-diaxial substituents due to stereoelectronic effect control. The stereoelectronic effect in the cyclic chelated transition state was probed and verified by tuning the steric bulkiness of the corresponding substituents. The reaction involving 1-nitrocyclohexene provided perfect support for the proposed diastereoselective control model. The current investigation provided not only comprehensive insights into the diastereoselective control in the sulfa-Michael addition of nitroalkenes and thiolates, but also an important role of the stereoelectronic effect in certain organic reactions involving cyclic chelate transition states.
Synthesis of (E)-nitro olefins by copper mediated addition-elimination reaction of organometallics to 2-nitro-1-phenylthiopropene
Stanetty, Peter,Kremslehner, Manfred
, p. 2491 - 2498 (1998)
The reaction of various organometallics with 2-nitro-1- phenylsulfonylpropene 2a and 2-nitro-1-phenylthiopropene 2b was investigated. While in the case of lithium and magnesium organyls the addition products 4 were formed, transmetallation with CuCN led exclusively to (E)-nitro olefins 3.
Diastereoselectivity in the triethylamine-catalyzed sulfa-Michael addition of thiols to nitroalkenes: Kinetic and thermodynamic control
Wang, Jiandong,Chen, Ning,Xu, Jiaxi
, p. 4007 - 4014 (2015/06/02)
The diastereoselectivity in the triethylamine-catalyzed sulfa-Michael addition of nitroalkenes and thiols was investigated. The sulfa-Michael addition is kinetic control at the beginning and thermodynamic control at the end for less bulky reactants. Thus,
Anti-Selective Michael Addition of Thiols and Their Analogues to Nitro Olefins
Kamimura, Akio,Sasatani, Hiroyuki,Hashimoto, Toshihiro,Kawai, Takashi,Hori, Kenzi,Ono, Noboru
, p. 2437 - 2442 (2007/10/02)
The reaction of nitro olefins with thiolate anions followed by protonation at -78 deg C gives anti-β-nitro sulfides.This procedure can be applied to the anti-selective preparation of β-nitro ethers and β-nitro selenides.The reaction of cyclic nitro olefins with aryl thiol gives cis-β-nitro sulfide in excellent selectivity.The conjugate addition of alkylaluminum reagents to phenylthio β-nitro olefins followed by protonation at -78 deg C also results in selective formation of anti-β-nitro sulfides.The anti isomers are also prepared through the deprotonation-protonation procedure at - 78 deg C from a mixture of syn- and anti-β-nitro-sulfides.The protonation process of the nitronate anion intermediates at -78 deg C is important for the occurence of high anti selectivity.However, the selectivity is not observed in the conjugate addition of an alkyl group to a simple nitro olefin.This difference in stereoselectivity can be explained on the basis of the differences of the preferable conformations of the nitronate anion intermediates.Theoretical calculations show that the methylthio group on β-position covers one side of the nitronate plane effectively to give the anti isomer in a stereoseletive way.
