Copper‐Catalyzed Stereoselective Defluorinative Borylation and Silylation of gem‐Difluoroalkenes

Abstract

The copper-catalyzed stereoselective defluorinative borylation and silylation of gem-difluoroalkenes was developed. The protocol led to the exclusive formation of Z type monofluoroalkenyl borons and silanes in generally good efficiency with broad substrate scope. The products formed could be readily transformed to other Fcontaining molecules by taking advantage of the versatile reactivities of CÀB and CÀSi bonds. Experimental and theoretical mechanistic studies were conducted which support an olefin insertion/ syn-planar b-F elimination pathway.

Regio‐ and Diastereoselective Synthesis of Cyclohexadienylborons via an Intermolecular Diels–Alder Reaction of Alkenyl MIDA Boronates with 2‐Pyrones

“…Likewise, the C−B bond could be oxidized to a C−Br bond with CuBr 2 in reasonable yields . Finally, phenylcyanide 10 was formed by C−B cyanation with Zn(CN) 2 in the presence of Cu(NO 3 ) 2 …”

“…Under slow‐release reaction conditions, Suzuki–Miyaura coupling of 5 a with phenyl iodide provided the terphenyl 8 in 52 % yield . Likewise, the C−B bond could be oxidized to a C−Br bond with CuBr 2 in reasonable yields . Finally, phenylcyanide 10 was formed by C−B cyanation with Zn(CN) 2 in the presence of Cu(NO 3 ) 2 …”

“…[19] Finally,p henylcyanide 10 was formed by CÀBc yanation with Zn(CN) 2 in the presence of Cu(NO 3 ) 2 . [19] In conclusion, we have developed as imple and efficient method for the formation of cyclohexadienylborons by a highly exo-selective intermoleculari nverse electron-demand Diels-Alder reaction of alkenyl MIDA boronates with 2-pyrones. Good functional-groupt olerance, broad substrate scope, excellent regio-and diastereoselectivity were observed.…”

Transition‐Metal‐Mediated and ‐Catalyzed C−F Bond Activation by Fluorine Elimination

“…[40] At the same time,t he group of Wang and Gao reported the Cu I -catalyzed defluorinative silylation of 1,1-difluoro-1-alkenes using Et 3 SiBpin as well as Cu I -catalyzed defluorinative borylation (Scheme 16). [41] Apart from successful applications to organoboron and organosilicon reagents,w ea chieved the double C À Fb ond activation of 2-trifluoromethyl-1-alkenes mediated by Ce III intermediates generated by transmetalation of organolithium reagents (Scheme 18). [42] Tr eatment of 2-trifluoromethyl-1alkenes with 2,2'-dilithiobiaryls in the presence of CeCl 3 affords fluorinated dibenzo [7]annulenes by ad omino S N 2'-S N Vr eaction by b-fluorine elimination.…”

Recent Advances in Transition Metal‐Catalyzed Functionalization of gem‐Difluoroalkenes

“…Defluorinative borylation and silylation of gem-difluoroalkenes also occur the using Cu-based catalyst systems with different oxidation states and using a spectrum of ligands and additives (Scheme 8). [17] A CuCl 2 and DPEphos derived system facilitate the borylation reaction, whereas a CuCl and PCy 3 derived system favored the silylation. Of note, the defluorinative silylation did not function with the aliphatic gem-difluoroalkene to give the silylated product (26 i), whereas borylation worked on the aliphatic system to afford product 27 i in 50 % yield.…”