Simple synthesis of 1,1-bis(trifluoromethyl)cyclopropanes

A new, simple synthesis of 1,1-bis(trifluoromethyl)cyclopropanes has been discovered. It is based on the reaction of readily available 2,2-bis(trifluoromethyl)thietanes with tertiary phosphines in a polar solvent, which leads to an unusual desulfurization process, resulting in the formation of 1,1-bis(trifluoromethyl)-2-alkoxy cyclopropanes. The process of the corresponding thietanes appears to be sensitive to the steric volume of the atom connected to carbon in α-position to sulfur.

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• New method for the synthesis of 1,1-bis(trifluoromethyl)cyclopropanes was developed.
• Reaction of fluorinated thietanes with phosphines results in the formation of cyclopropanes.
• Plausible mechanism of new process is suggested.