REGIOSELECTIVE AND CHEMOSELECTIVE EPOXIDATION OF FLUORINATED MONOTERPENES AND SESQUITERPENES BY DIOXIRANES

A comparative study on chemoselectivity of dimethyldioxirane (DMD) and methyl(trifluoromethyl)dioxirane (TFMD) in the epoxidation of trisubs tituted C=C bords presenting different activation in fluorinated monot erpene and sesquiterpene derivatives has been carried out. With respec t to DMD, epoxidations performed with TFMD were faster under milder co nditions, although high conversion yields were obtained with both reag ents. In ease of epoxidation of unsaturated moieties the trend observe d was: (CH3)(R1)C = CH(R2) congruent-to (CH3)(R1)C = CH(CH2OR) congrue nt-to (CH3)(R1)C = CF(R2) much greater than (CH3)(R1)C = CH(COOR) > (C F3)(R1)C = CH(R2). Results reported herein present the first example o f direct epoxidation of a double bond bearing a CF3 substituent by non -biochemical means.