Facile Access to AgOCF₃ and Its New Applications as a Reservoir for OCF₂ for the Direct Synthesis of N−CF₃, Aryl or Alkyl Carbamoyl Fluorides

Abstract

The development of innovative fluorination strategies is greatly dependent also on the availability, safety and practicability of available fluorinating reagents. We herein show a straightforward and quantitative strategy for the preparation of valuable AgOCF3 at room temperature and showcase its performance in trifluoromethoxylations or as reservoir for O=CF2. This enabled the direct, practical and safe synthesis of valuable N‐alkyl/aryl and N−CF3 carbamoyl fluorides from secondary amines and isothiocyanides, respectively. Our mechanistic data indicate that AgOCF3 does not liberate O=CF2 until it is activated by a nucleophilic co‐reagent, reinforcing the stability of the salt under our new preparation strategy.

Stable and Storable N(CF3)2 Transfer Reagents

“…So far, only few Cu I and Ag I metal complexes with the trifluoromethoxy ligand like [(Ph t Bu 2 P)(bpy)AgOCF 3 ] [25] are known (Figure 1). [25–27] The small number of structurally characterized complexes is due to the low stability of the OCF 3 – ion that easily loses F – while releasing carbonyl fluoride (difluorophosgene), which enabled the use of AgOCF 3 as C(O)F 2 source [28] . This synthetic useful reaction is similar to the decomposition of perfluoroalkyl ions into perfluoroalkenes and fluoride, for example the generation of tetrafluoroethylene from the pentafluoroethyl ion.…”

“…In contrast to perfluoroalkyl and perfluoroalkoxy groups, the chemistry of related perfluoroalkyl nitrogen substituents has been studied to a much lesser extent. Some synthetic strategies towards N ‐trifluoromethylamines and related N ‐perfluoroalkylnitrogen derivates have been developed in recent years [28–38] . Efficient strategies towards N , N ‐bis(perfluoroalkyl)nitrogen compounds remain scarce, presumably, because of the lack of suitable starting materials [18,39–40] .…”

“…Some synthetic strategies towards N ‐trifluoromethylamines and related N ‐perfluoroalkylnitrogen derivates have been developed in recent years. [ 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 ] Efficient strategies towards N , N ‐bis(perfluoroalkyl)nitrogen compounds remain scarce, presumably, because of the lack of suitable starting materials. [ 18 , 39 , 40 ] Especially the N , N ‐bis(trifluoromethyl)amino group is of interest as its organic derivatives are known to exhibit high stability, for example against acids and bases,[ 1 , 41 ] and because its potential as substituent in pharmaceuticals was demonstrated, earlier.…”

Direct Trifluoromethoxylation without OCF3‐Carrier through In Situ Generation of Fluorophosgene

“…Interestingly, the final stock solution of this salt was shown to be very stable and could be used in trifluoromethoxylations and other reactions; however, a filtration of insoluble silver salts in a glovebox was required. [31] Consequently, an efficient process combining the formation of both COF 2 and then F 3 CO À , and the direct use of the latter in trifluoromethoxylation, altogether in situ without the intermediate formation and isolation of a trifluoromethoxylating reagent, would still be highly valuable. We describe herein our efforts towards this aim (Figure 2).…”

“…reported, in line with Hu's work, the ex situ preparation of AgOCF 3 by mixing triphosgene and silver fluoride. Interestingly, the final stock solution of this salt was shown to be very stable and could be used in trifluoromethoxylations and other reactions; however, a filtration of insoluble silver salts in a glovebox was required [31] …”