Selective C–F Bond Allylation of Trifluoromethylalkenes

Abstract

Selective CÀF bond functionalization of CF 3 group represents an appealing strategy for the incorporation of pharmaceutically privileged difluoromethylene moiety. Despite the recent significant advancement attained in the functionalization of Ar-CF 3 molecules, prescriptions amenable for alkenyl-CF 3 congeners remain sufficiently inadequate. Herein, we report a strategically novel protocol for the CÀF bond elaboration of trifluoromethylalkene derivatives. By using readily available allyl metallics as nucleophilic coupling partner, the present reaction enables an expedient construction of structurally diversified CF 2 -bridged 1,5-dienes. Furthermore, the exquisite selectivity observed in this transformation is revealed to be based on the underlying mechanism that consists of a cascade of nucleophilic S N 2' defluorinative allylation and electronically promoted Cope rearrangement.

Nickel‐Catalyzed Unsymmetrical Bis‐Allylation of Alkynes

“…[23] In addition, the defluorination of 4 aa with LiAlH 4 was observed in excellent stereoselectivity (> 20 : 1 E/Z), giving 68 % yield of mono-fluoro substituted alkene 15. [24] The stereo configuration of product 15 was determined by NOE spectra (see Supporting Information for details). Notably, by choosing proper catalyst, the chemoselective hydrogenation was also a touchable task.…”

Synthesis of Mono‐fluoroallenes through Copper‐Catalyzed Defluorinative Silylation of α,α‐Difluoroalkylalkynes

“…[ 12 ] Our group has long been interested in the selective C—F bond activation. [ 13 ] In 2017, we reported a rhodium‐catalyzed [4 + 1] annulation reaction with gem ‐difluoromethylene alkynes, which are readily prepared from terminal alkynes, as an uncommon C1 unit for the construction of isoindolin‐1‐one derivatives. Mechanistic study suggested successive dual C—F bond cleavage as the crucial steps for the transformation.…”