Methyltrioxorhenium-Catalyzed Epoxidation of Homoallylic Alcohols with Hydrogen Peroxide

Abstract

Homoallylic alcohols were efficiently converted to the corresponding 3,4-epoxy alcohols in excellent yields by methyltrioxorhenium (MTO)-catalyzed epoxidation with aqueous hydrogen peroxide as the terminal oxidant and 3-methylpyrazole (10 mol %) as an additive. The epoxidations of homoallylic alcohols proceeded under organic solvent-free conditions faster than those in dichloromethane.

Regio- and Stereoselective Monoepoxidation of Dienes using Methyltrioxorhenium: Synthesis of Allylic Epoxides

“…It was evident that methyltrioxorhenium (MTO) (entry 1) in CH 2 Cl 2 was the most efficacious for distal epoxidation, although the product was generated as a mixture of diastereomers 2 and 3 . , Yields were diminished somewhat in CH 3 CN and CH 3 NO 2 , and the dr ( 2 / 3 ) was unchanged. Other common reagents (entries 2–5) were ineffective or gave minor amounts of epoxide.…”

Methyltrioxorhenium (MTO) catalysis in the epoxidation of alkenes: a synthetic overview

“…H 2 O 2 and 3-methylpyrazole (3-MePz) additive (10 mol%) to obtain 3,4-epoxy alcohols, which are utilized as a synthetic intermediate in many reactions (Scheme 18). 42 The method was found to be well suited to a variety of internal and terminal olefins to afford good yields of the epoxides under solvent-free (neat) conditions. Moreover, di-and tri-substituted olefins provided good yields (up to 90%) of epoxides using 0.1-0.2 mol% of MTO.…”

Regio- and Stereoselective Addition of HO/OOH to Allylic Alcohols

“…For this reason, installation of epoxy functionality sometimes also becomes an indispensable part of the whole synthetic plan and thus holds, though in an inexplicit way, a special place in the synthesis of organic peroxides. During the course of studies on perhydrolysis of epoxides, we became aware of those protocols of, e.g., Scettri (Ti­(OiPr) 4 ), Yamamoto (VO­(OiPr) 3 , WO 2 (acac) 2 ), and Yamazaki (MTO, methyltrioxorhenium), where allylic or homoallylic alcohols reacted smoothly with H 2 O 2 in the presence of a proper transition metal catalyst to furnish corresponding epoxides. These findings prompted us to consider whether molybdenum species could also promote epoxidation of alkenes in ethereal H 2 O 2 should it be possible to form epoxides under the perhydrolysis conditions, the epoxidation and the perhydrolysis might occur in one flask and thus tremendously simplify the overall synthesis.…”