Chemistry of [(perfluoroalkyl)methyl] oxiranes. Regioselectivity of ring opening with O-nucleophiles and the preparation of amphiphilic monomers

Abstract

The reactions of oxiranes R FCH 2CH(–O–)CH 2 (R F≡C 4F 9, C 6F 13, C 8F 17; 4a– 4c) with a series of alkanols in the presence of a Lewis acid took place at the terminal carbon atom with complete regioselectivity. 2-Hydroxyethyl methacrylate and acrylate reacted similarly. The reaction with alkane diols was controlled to proceed with one or two molecules of the oxiranes chemoselectively. Non-regioselective, base-catalysed ring opening by methacrylic acid (83% terminal attack) was discussed on the basis of the hard and soft acids and bases (HSAB) concept. A convenient transformation of the oxiranes to the corresponding diols 13a– 13c via dioxolane intermediates, and their conversion to bis-methacrylates, was accomplished with overall yields of 75%–79%. Thiourea converted the oxiranes into the corresponding thiiranes ( 15a– 15c). The reactions afforded products generally in yields of 82%–98%.