PaaSicats: Powerful catalysts for asymmetric epoxidation of enones. Novel syntheses of α-arylpropanoic acids including (S)-fenoprofen
摘要:
Application of the recently developed silica-adsorbed polyleucine catalysts to the enantioselective epoxidation of Two enones is reported. Treatment of these epoxides with trimethylaluminium in moist dichloromethane generates the alpha-hydroxy-beta-methylketones, with inversion of configuration. Diastereoselective reduction of the ketone moiety followed by oxidative cleavage generates alpha-arylpropanoic acids. (C) 1999 Elsevier Science Ltd. All rights reserved.
A highly efficient catalytic kinetic resolution of 2,3-epoxy 3-aryl ketones via asymmetric ring-opening with pyrazole derivatives has been achieved by using a chiral N,N′-dioxide–Sc(iii) complex as the catalyst.
Chiral octahedral complexes of Co(<scp>iii</scp>) as catalysts for asymmetric epoxidation of chalcones under phase transfer conditions
作者:Vladimir A. Larionov、Elina P. Markelova、Alexander F. Smol'yakov、Tat'yana F. Savel'yeva、Victor I. Maleev、Yuri N. Belokon
DOI:10.1039/c5ra11760g
日期:——
Stereochemically inert and positively charged chiralcomplexes of Co(III) were shown to catalyze the asymmetric epoxidation of chalcones with H2O2 under phase transfer conditions. The reaction products had enantiomeric purities of up to 55%. It was also shown that complex 1a I− catalyzed the coupling reaction of a resulting epoxide with CO2 (conversion 72%).
在相转移条件下,Co(III)的立体化学惰性和带正电荷的手性配合物可催化查耳酮与H 2 O 2的不对称环氧化。反应产物的对映体纯度高达55%。它也表明,复杂1A我-催化的与CO所得环氧化物的偶联反应2(转化72%)。
Enantioenriched (S)-6,6′-diphenylBinol-Ca: a novel and efficient chirally modified metal complex for asymmetric epoxidation of α,β-unsaturated enones
A novel enantioenriched-Ca complex was generated using low cost commercially available CaCl, and the potassium salt of (S)-6,6'-diphenylBINOL and its application to alpha,beta-unsaturated enone epoxidation is described. Furthermore the absolute stereochemistry of (S)-6,6'-diphenylBINOL has been corrected and unequivocally established by single crystal X-ray analysis, 500 MHz NMR spectroscopy and mass spectra. The enantiomeric excess (ee) was determined by H-1 NMR spectroscopy of its corresponding MTPA ester and was found to be >98%. (C) 2003 Elsevier Ltd. All rights reserved.
Stereocontrolled ring-opening of some enantiomerically enriched epoxy ketones and epoxy alcohols using trimethylaluminium: synthesis of (S )-2-arylpropanoic acids
作者:Lydia Carde、D. Huw Davies、Stanley M. Roberts
DOI:10.1039/b000996m
日期:——
cleavage furnished (S)-2-phenylpropanoic acid 11. In a complementary sequence epoxy ketones (−)-6 and 25 were converted into (S)-2-phenylpropanoic acid and (S)-fenoprofen 5 respectively by reduction with zinc borohydride, reaction with trimethylaluminium and oxidative cleavage. Similarly epoxy ketones (−)-6, 21 and 28 were treated with methylmagnesiumiodide, trimethylaluminium and the resultant alcohols subjected
PaaSicats: Powerful catalysts for asymmetric epoxidation of enones. Novel syntheses of α-arylpropanoic acids including (S)-fenoprofen
作者:Lydia Carde、Huw Davies、Thomas P. Geller、Stanley M. Roberts
DOI:10.1016/s0040-4039(99)01022-9
日期:1999.7
Application of the recently developed silica-adsorbed polyleucine catalysts to the enantioselective epoxidation of Two enones is reported. Treatment of these epoxides with trimethylaluminium in moist dichloromethane generates the alpha-hydroxy-beta-methylketones, with inversion of configuration. Diastereoselective reduction of the ketone moiety followed by oxidative cleavage generates alpha-arylpropanoic acids. (C) 1999 Elsevier Science Ltd. All rights reserved.