A Facile Approach to 2-CF3-Substituted Seven-membered Oxacycles via Stereoselective Preparation and Cope Rearrangement of 2-CF3-cis-2,3-Bis(alkenyl)oxiranes
Stereoselective generation of cis-2-lithio-3-CF3-oxirane via CF3-substituted β-oxido carbenoids. Highly stereoselective synthesis of CF3-substituted tri- and tetrasubstituted oxiranes and tetrasubstituted alkenes
1,1-trifluoropropan-2-ols with organolithium reagents R2Li in THF at −98°C stereoselectively produces 2,3-disubstituted 2-lithio-3-trifluoromethyloxiranes with Li and CF3cis. The reagents react with electrophiles El-X or organoboranes R3BR2 to give CF3-containingtri- and tetrasubstitutedoxiranes or tetrasubstitutedalkenes, respectively, with high diastereoselectivities.
A Facile Approach to 2-CF<sub>3</sub>-Substituted Seven-membered Oxacycles via Stereoselective Preparation and Cope Rearrangement of 2-CF<sub>3</sub>-<i>cis</i>-2,3-Bis(alkenyl)oxiranes
Stereoselective preparation and Cope rearrangement of 2-CF3-substituted cis-2,3-bis(alkenyl)oxiranes provides a convenient route to a diverse of 2-CF3-4,5-dihydrooxepins. The reaction sequence followed by reduction or oxidation provides 2-CF3-substituted oxepanes or oxepins, respectively.