Gold-catalyzed electrophilic activation of 1,1-difluoroallenes: α- and γ-selective addition of heteroatom nucleophiles

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

“…[ 3 ] Early endeavors for the preparation of fluorinated allene include difluorovinylidenation of aldehydes and ketones, [ 4 ] indium‐mediated S E 2’ or magnesium organocuprate S N 2’ substitution of gem ‐difluoropropargyl bromide, [ 5‐7 ] aldol reaction of alkynylenolate, [ 8 ] Shapiro reaction of trifluoromethylketones, [ 9 ] Horner–Wadsworth–Emmons reaction of ketenes, [ 10 ] and others. [ 11 ] However, the heavy reliance on elaborated starting materials and/or strong nucleophiles of these methods results in the poor functional group tolerance and largely limits their broad application. Thus, the development of general, efficient and mild synthesis of fluorinated allenes based on easily accessible starting materials is still highly desirable.…”

Discussion Addendum for: Preparation of 1,1-Difluoroallenes by Difluorovinylidenation of Carbonyl Compounds

“…As well as undergoing alkylation, borylation, and silylation reactions, 1,1-difluoroallenes underwent the g-selective addition of benzamide and thiophenol in the presence of an Au(I) [or an Au(III)] catalyst through cationic intermediates (Scheme 9, see also: Scheme 5). 11 3,3-Difluoroallylic amine 26 and thioether 27 were synthesized in 81% and 72% yields, respectively. The use of a Rh(I) catalyst with a chiral phosphine ligand aided in the synthesis of chiral 3,3-difluoroallylic thioether 28 via g-selective C-S bond formation (Scheme 10, see also: Scheme 8).…”

Rhodium-catalyzed asymmetric hydroamination of gem-difluoroallenes with anilines

“…In this context, Hartwig and co-workers first described an iridium-catalyzed enantioselective allylic substitution of 3,3-difluoropropenes with carbon nucleophiles via monofluoro π-allyl species using F atom as a leaving group (Figure 1c) [58]. Inspired by this result, we envisioned that allenes bearing two geminal-difluoro groups [59][60][61][62][63][64][65] could be applied as the precursors of π-allyl species to form gem-difluoroallylic amines through hydroamination [67][68][69].…”