Accessible sugars as asymmetric olefin epoxidation organocatalysts: glucosaminide ketones in the synthesis of terminal epoxides.

نویسندگان

  • Omar Boutureira
  • Joanna F McGouran
  • Robert L Stafford
  • Daniel P G Emmerson
  • Benjamin G Davis
چکیده

A systematically varied series of conformationally restricted ketones, readily prepared from N-acetyl-D-glucosamine, were tested against representative olefins as asymmetric epoxidation catalysts showing useful selectivities against terminal olefins and, in particular, typically difficult 2,2-disubstituted terminal olefins.

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

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Enantioselective synthesis of 2,2-disubstituted terminal epoxides via catalytic asymmetric Corey-Chaykovsky epoxidation of ketones.

Catalytic asymmetric Corey-Chaykovsky epoxidation of various ketones with dimethyloxosulfonium methylide using a heterobimetallic La-Li(3)-BINOL complex (LLB) is described. The reaction proceeded smoothly at room temperature in the presence of achiral phosphine oxide additives, and 2,2-disubstituted terminal epoxides were obtained in high enantioselectivity (97%-91% ee) and yield ( > 99%-88%) f...

متن کامل

Design and Synthesis of Binaphthol-Derived Chiral Ketone Catalysts for Dioxirane-Mediated Asymmetric Epoxidation of Olefins

Binaphthol-derived chiral ketones 1a-c were synthesized and were shown to serve as active catalysts for asymmetric epoxidation of olefins using Oxone®, although their enantioselectivities were not high. However, very interestingly, the stereochemical outcome of the resulting epoxides implicates that in the epoxidation using 1ac, the planar transition state may be more favorable than the spiro t...

متن کامل

Selective synthesis of functionalized, tertiary silanes by diastereoselective rearrangement-addition.

[reaction: see text] Treatment of hydroxy-substituted silyl epoxides with Grignard reagents induces a 1,2-carbon shift to reveal alpha-silyl aldehydes, which are trapped by highly diastereoselective addition reactions of the Grignard reagent. The starting epoxides are readily accessible from propargylic alcohols by regio- and diastereoselective hydrosilylation and epoxidation reactions. In addi...

متن کامل

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 qua...

متن کامل

An efficient ketone-catalyzed epoxidation using hydrogen peroxide as oxidant.

Epoxides are very important building blocks in organic synthesis.1 Dioxiranes, either isolated or generated in situ, have been shown to be extremely versatile epoxidation reagents.2-6 In nearly every case, the generation of dioxiranes uses potassium peroxomonosulfate (KHSO5) as oxidant (Scheme 1).7,8 During our recent study on asymmetric epoxidation using the fructose-derived ketone (1), we fou...

متن کامل

ذخیره در منابع من


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

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

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • Organic & biomolecular chemistry

دوره 7 20  شماره 

صفحات  -

تاریخ انتشار 2009