Susceptibility to metabolism is a common issue with the tert-butyl group on compounds of medicinal interest. We demonstrate an approach of removing all the fully sp(3) C-Hs from a tert-butyl group: replacing some C-Hs with C-Fs and increasing the s-character of the remaining C-Hs. This approach gave a trifluoromethylcyclopropyl group, which increased metabolic stability. Trifluoromethylcyclopropyl-containing analogues had consistently higher metabolic stability in vitro and in vivo compared to their tert-butyl-containing counterparts.
An efficient room-temperature Pd-catalyzed Suzuki–Miyaura cross-coupling reaction of aryl-boronic acids with aryl chlorides is communicated here. The Pd(OAc)2/NiXantphos catalyst system enables the coupling reaction at room temperature in good to excellent yields (average yield >90%).