A Highly Diastereoselective and Enantioselective Phase-Transfer Catalyzed Epoxidation of β-Trifluoromethyl-β,β-disubstituted Enones with H2O2

نویسندگان

  • Fu-Xue Chen School of Chemical Engineering & the Environment, Beijing Institute of Technology, Haidian District, Beijing 100081, CHINA
  • Pran Gopal Karmaker School of Chemical Engineering & the Environment, Beijing Institute of Technology, Haidian District, Beijing 100081, CHINA
  • Qi Wang School of Chemical Engineering & the Environment, Beijing Institute of Technology, Haidian District, Beijing 100081, CHINA
  • Shaoxiang Wu School of Chemical Engineering & the Environment, Beijing Institute of Technology, Haidian District, Beijing 100081, CHINA
  • Yao-Feng Wang School of Chemical Engineering & the Environment, Beijing Institute of Technology, Haidian District, Beijing 100081, CHINA
چکیده مقاله:

Trifluoromethylated organic compounds, especially chiral quaternary alcohols bearing trifluoromethyl group are of important intermediates in drugs, agrochemicals and etc.An efficient epoxidation of β-CF3-β,β-disubstituted unsaturated ketones (6) has been developed with environmental benign hydrogen peroxide as the oxidant and F5-substituted chiral quaternary ammonium salt (1g or 5) derived from cinchona-alkaloid as the catalyst. Using 3 mol% of the catalyst, both enantiomers of(R,R) and (S,S) β-trifluoromethyl-α,β-epoxy ketones (7, 8) were obtained in excellent diastereoselectivities (up to 100:1 d.r.) and enantioselectivities (up to 99.7% ee). The effects of catalyst structure, catalyst loading, substrate structure, the nature of oxidant, and reaction conditions on the catalyst capacities have been discussed in full length. The reaction mechanism was proposed to explain the origin of chiral induction. By subsequent reduction with zinc the epoxides are exhibited to be converted into trifluoromethylated quaternary alcohols without any loss in enantioselectivities. All new compounds are fully characterized by IR, NMR, elemental analysis and or high resolution mass spectrum.

برای دانلود باید عضویت طلایی داشته باشید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

a highly diastereoselective and enantioselective phase-transfer catalyzed epoxidation of β-trifluoromethyl-β,β-disubstituted enones with h2o2

trifluoromethylated organic compounds, especially chiral quaternary alcohols bearing trifluoromethyl group are of important intermediates in drugs, agrochemicals and etc.an efficient epoxidation of β-cf3-β,β-disubstituted unsaturated ketones (6) has been developed with environmental benign hydrogen peroxide as the oxidant and f5-substituted chiral quaternary ammonium salt (1g or 5) derived from...

متن کامل

Catalytic highly enantioselective transfer hydrogenation of β-trifluoromethyl nitroalkenes. An easy and general entry to optically active β-trifluoromethyl amines.

In the presence of a thiourea catalyst, β-CF3 nitroalkenes react with Hantzsch esters in a highly enantioselective fashion, giving a broad range of β-CF3 amine precursors with a tertiary stereocentre at the β-position. This reaction represents the first general catalytic enantioselective approach to this important class of β-CF3 amines.

متن کامل

Highly Diastereo- and Enantioselective Synthesis of Trifluoromethyl-Substituted Cyclopropanes via Myoglobin-Catalyzed Transfer of Trifluoromethylcarbene.

We report an efficient strategy for the asymmetric synthesis of trifluoromethyl-substituted cyclopropanes by means of myoglobin-catalyzed olefin cyclopropanation reactions in the presence of 2-diazo-1,1,1-trifluoroethane (CF3CHN2) as the carbene donor. These transformations were realized using a two-compartment setup in which ex situ generated gaseous CF3CHN2 is processed by engineered myoglobi...

متن کامل

Highly enantioselective copper(I)-catalyzed conjugate addition of 1,3-diynes to α,β-unsaturated trifluoromethyl ketones.

The conjugate diynylation of α,β-unsaturated trifluoromethyl ketones is carried out in the presence of a low catalytic load (2.5 mol%) of a copper(I)-MeOBIPHEP complex, triethylamine and a terminal 1,3-diyne. Pre-metalation of the terminal 1,3-diyne with stoichiometric or higher amounts of dialkylzinc reagent is not required. The corresponding internal diynes bearing a propargylic stereogenic c...

متن کامل

Enantioselective palladium catalyzed conjugate additions of ortho-substituted arylboronic acids to β,β-disubstituted cyclic enones: total synthesis of herbertenediol, enokipodin A and enokipodin B.

The palladium-catalyzed conjugate addition (Michael addition) of ortho-substituted arylboronic acids to β,β-disubstituted cyclic enones, in particular 3-methyl cyclopent-2-enone and 3-methyl cyclohex-2-enone, is reported. With an achiral bipyridine-based palladium catalyst, good yields are obtained with a variety of ortho-substituted arylboronic acids. In the asymmetric version, good to very hi...

متن کامل

Highly enantioselective epoxidation of 2-methylnaphthoquinone (vitamin K3) mediated by new cinchona alkaloid phase-transfer catalysts.

In the area of catalytic asymmetric epoxidation, the highly enantioselective transformation of cyclic enones and quinones is an extremely challenging target. With the aim to develop new and highly effective phase-transfer catalysts for this purpose, we conducted a systematic structural variation of PTCs based on quinine and quinidine. In the total of 15 new quaternary ammonium PTCs, modificatio...

متن کامل

منابع من

با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

ذخیره در منابع من قبلا به منابع من ذحیره شده

{@ msg_add @}


عنوان ژورنال

دوره 34  شماره 4

صفحات  13- 38

تاریخ انتشار 2015-12-01

با دنبال کردن یک ژورنال هنگامی که شماره جدید این ژورنال منتشر می شود به شما از طریق ایمیل اطلاع داده می شود.

میزبانی شده توسط پلتفرم ابری doprax.com

copyright © 2015-2023