Metal-free radical perfluoroalkylation of (hetero)arenes

Abstract

We report a metal-free radical perfluoroalkylation method which uses inexpensive and commercially available perfluorocarboxylic anhydrides as an easy to use source of perfluoroalkyl radicals.

Perfluoroalkylation reactions of (hetero)arenes

“…Bräse and collaborators 29 have very recently introduced a metal-free radical peruoroalkylation method of (hetero)arenes which employs commercially available peruorocarboxylic anhydrides as source of peruoroalkyl radicals. 30 The scope of the transformation is illustrated in Scheme 4.…”

“…3 Radical homolytic triuoromethylation reactions of aromatic nuclei have been intensively studied and many recent review articles do exist in this area. 1) or else be non-metal catalyzed, among which, the use of the Baran reagent 14 or per-uoroalkylsulnate salts 15 in the presence of organic peroxide 16 or azo initiators 17 (Fig. 5-8 C Ar-H peruoroalkyl-group radical substitution reactions of arenes can be classied into thermal and photoinduced methods.…”

“…5-8 C Ar-H peruoroalkyl-group radical substitution reactions of arenes can be classied into thermal and photoinduced methods. [12][13][14][15][16][17][18] Photoinduced methods either through direct homolysis of X-C n F 2n+1 bonds, 19,20 or by means of photoinduced electron transfer (PET) reactions 21 are capable of generating per-uoroalkyl radicals C n F 2n+1 even in aqueous systems 22 (Fig. 1) or else be non-metal catalyzed, among which, the use of the Baran reagent 14 or per-uoroalkylsulnate salts 15 in the presence of organic peroxide 16 or azo initiators 17 (Fig.…”

Perfluoroalkylation of Unactivated Alkenes with Acid Anhydrides as the Perfluoroalkyl Source

“…[8] Indeed, oxidized TFAAs such as bis(trifluoroacetyl) peroxide (BTFAP) [9][10][11] and ap yridine Noxide/TFAA adduct [12] have been used as trifluoromethyl radical sources for the trifluoromethylation of aromatic compounds and limited types of alkenes. [8] Indeed, oxidized TFAAs such as bis(trifluoroacetyl) peroxide (BTFAP) [9][10][11] and ap yridine Noxide/TFAA adduct [12] have been used as trifluoromethyl radical sources for the trifluoromethylation of aromatic compounds and limited types of alkenes.…”

“…[11][12][13][14] However, trifluoromethylation of alkenes,i np articular those that are unactivated, with TFAA as atrifluoromethyl source remains an important challenge.Indeed, our preliminary examination of the reaction of an unactivated alkene 1a with BTFAP generated in situ from TFAA and urea·H 2 O 2 [10,15] was unsuccessful, and alarge amount of starting material was recovered along with acomplex mixture of trifluoromethylated products (Scheme 1a). Theo bserved low product selectivity suggests that an acceleration of CF 3 radical generation as attempted in the aromatic trifluoromethylations [9][10][11][12][13][14] is not sufficient to achieve trifluoromethylation of unactivated alkenes. Theo bserved low product selectivity suggests that an acceleration of CF 3 radical generation as attempted in the aromatic trifluoromethylations [9][10][11][12][13][14] is not sufficient to achieve trifluoromethylation of unactivated alkenes.…”