Synthesis of Trifluoromethyl-Substituted Cyclopropanes

Significance

Methods for selective introduction of fluoroalkyl groups into organic molecules are highly desirable. In the formation of fluoroalkyl cyclopropanes, the best results so far showed 75% ee (P. Le Maux, S. Julliard, G. Simoneaux Synthesis 2006, 1701). The Rh₂(PTAD)₄ catalyst system developed by Davies was unique in producing the chiral cyclopropane 3 in both high yield and enantioselectivity. Furthermore, a single diastereomer was observed. The nature of the aryl groups on the reacting partners did not have a significant impact on the enantioselectivity, except in the case of electron-rich alkenes (3a: 88% ee).