0 Hits

  • Previous / Next

You are using Science Of Synthesis as a Guest.
Please login to access the full content or check if you have access via Using Chloroperoxidase

DOI: 10.1055/sos-SD-201-00018

Matsumoto, K.; Katsuki, T.; Arends, I. W. C. E.Science of Synthesis: Stereoselective Synthesis, (20111116.

Epoxidation with monooxygenases depends on cofactors. The enzymes usually consist of several subunits that, in a series of cascades, provide the reducing equivalents to the iron-active site. The need for a cofactor is eliminated in the case of peroxidases, for which hydrogen peroxide acts as the oxidant. The hydrogen peroxide results in a shunt pathway that directly restores the [P+Fe(IV)=O] species from iron(III) (see Scheme 61). Because of its ease of handling, chloroperoxidase (CPO) from Caldariomyces fumago is an attractive option; it is commercially available, and displays a reasonable substrate range.[‌163‌] The main problems are its instability under the reaction conditions and its sluggish reaction rates. Typical turnover rates are 0.12s1. The epoxidation of styrene in the presence of 0.8% of surfactant is, at 5.5s1, the fastest on record.[‌164‌] The advantage of this reaction is that the enantioselectivities are, in most cases, good to excellent. For example, hept-2-ene can be oxidized with 1700 turnovers relative to enzyme in 30% tert-butyl alcohol to give the corresponding epoxide with 96% ee. The total turnover number of this reaction can be increased from 1700 to 11500 when hydrogen peroxide is generated in situ by a glucose oxidase mediated reaction of glucose and oxygen. A wide range of 2-methylalk-1-enes can be oxidized with enantiomeric excess values ranging from 50 to 95% (Scheme 66).[‌165‌‌167‌]

Meeeee 88 Meeeeeeeeee ee Meeeeee ee Meeeeeeeeeeeeeee Meeeee[‌888‌‌888‌]

Meeeeeeeeee 88

M8 M8 M8 Meeeeeeee Meee (e) ee (%) Meeeee Meeee (%) Mee
Me Me M 88% M8M8 8 88 8M,8M 88 [‌888‌]
(MM8)8Me Me M 88% M8M8 8 88 8M,8M 88 [‌888‌]
(MM8)8Me M Me 88% M8M8 8.88 88 M 88 [‌888‌]
MM8MM8Me M Me 88% M8M8 8.88 88 M 88 [‌888‌]
MM8Me M Me 88% M8M8 8.88 88 M 88 [‌888‌]
MM8Me M Me e-MeMMM 8 88 M 88 [‌888‌]

e Mee ee 88% M8M8: eeeeee (8 eM) eee MMM eeeeee (8.888eee%) eeee eeeeeee ee e 8:8 eeeeeee ee eeeeeee/eeeeeee eeeeee (eM8.8) ee ee; 88% M8M8 eee eeeeeeeeeeee eeeee ee e eeeee eeeeeee/eeeeeeeee eeeee ee 8.8:8. Mee ee e-MeMMM: e-MeMMM (8 eeeee) eee eeee ee eee eeeeeee ee eeeeeee eeeeee (eM8.8) eeee 8.8M eeeeee eee 8.88eee% MMM eeeeee.