137494-01-0Relevant academic research and scientific papers
Application of chiral TADDOL ligand and rare earth metal amide in combined catalysis of asymmetric reaction
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Paragraph 0180-0183, (2020/11/23)
The invention relates to application of chiral TADDOL ligand and rare earth metal amide in combined catalysis of asymmetric epoxidation reaction of chalcone compounds. According to the application, alpha, beta-unsaturated ketone shown in a formula (1) and tert-butyl hydroperoxide react in the presence of organic alkali under the combined catalytic action of a chiral TADDOL ligand shown in a formula (3) and rare earth metal amide in an anhydrous, oxygen-free and protective atmosphere to obtain the chiral epoxy compound shown in the formula (2) after the reaction is completed, wherein R1 is selected from hydrogen, alkyl, halogen, alkoxy, trifluoromethyl, nitro or cyano, R2 is selected from phenyl, substituted phenyl, naphthyl, furyl or thienyl; R3 and R4 are respectively and independently selected from alkyl, phenyl or R3 and R4 and carbon atoms connected with R3 and R4 form naphthenic base; Ar is phenyl, substituted phenyl, biphenyl or naphthyl; the molecular formula of the rare earth metal amide is RE [N (SiMe3) 2] 3. The method has the advantages of wide substrate application range, high yield and high enantioselectivity.
Triphenylbismuthonium 2-Oxoalkylide, A Moderately Stabilized Bismuthonium Ylide: Generation and Reactions with Some Electrophiles
Matano, Yoshihiro
, p. 2703 - 2710 (2007/10/02)
Treatment of (2-oxoalkyl)triphenylbismuthonium tetrafluoroborates 3 with potassium tert-butoxide in tetrahydrofuran at -78 deg C produced triphenylbismuthonium 2-oxoalkylides 4, which readily underwent epoxidation with the aldehydes 5 to give the α,β-epoxy ketones 7 with highly trans selectivity.The ylide 4a reacted with dimedone 11, the sulfonic acid 13, the thiol 15 and the isocyanate 17 to afford the corresponding ketones 12, 14, 16 and 19 in moderate to good yields.Reaction of the ylide 4c with the α,β-unsaturated ketones 10 and 21 afforded the 1,2-dibenzoyl- and the 1,2,3-tribenzoyl- cyclopropanes 20 and 22, respectively, although the yields were low.In the presence of a catalytic amount of nitrosobenzene 23, the ylide 4a a unique decomposition to give the 2,2,7,7-tetramethyloct-4-ene-3,6-dione 24 in quantitative yield, while the reaction with the nitrile oxide 25 yielded the isoxazoline 26.In all of these reactions, triphenylbusmuthane 6 was the additional major product.
Synthetic Enzymes. Part 2. Catalytyc Asymmetric Epoxidation by means of Polyamino-acids in a Triphase System
Julia, Sebastian,Guixer, Joan,Masana, Jaume,Rocas, Jose
, p. 1317 - 1324 (2007/10/02)
The asymmetric epoxidation of several chalcones and other electron-poor olefins, in the presence of catalytic amounts of poly-(S)-amino-acids in a triphase system with optical yields of up to 96percent is described.The influence of the molecular structure of the catalysts and substrates, the solvent, and the temperature on the stereochemistry is discussed.
