Visible-Light-Induced Copper-Catalyzed Intermolecular Three-Component Difluoroalkyl Thiocyanidation of Alkenes

Abstract

In this report, we develop a new strategy for visiblelight-induced, copper-catalyzed three-component difluoroalkyl thiocyanidation of alkenes to construct a series of important difluorothiocyanate compounds. The new approach can also be applied to perfluorothiocyanate compounds, even target molecules containing drug/natural product skeletons. Mechanistic studies provide that the copper complex plays a dual role, as both the photoredox catalyst for electron transfer and the cross-coupling catalyst for C−SCN bond formation.

A general Fe-catalysed azidation of iododifluoroketones and its utilization for the synthesis of gem-difluoromethylenated triazoles

“…2,3 In particular, as a low-cost and widely available difluoroalkyl source, gem -difluoroalkyl halides have been extensively studied for the difluoroalkylation reactions, such as the transition-metal-catalysed cross-coupling with organoborons/halides 4 and photoredox radical addition to unsaturated C–C bonds, 5 leading to the formation of a new CF 2 –C bond. 6 Recently, increasing attention has been paid to the development of accesses to heteroatom-bound motifs such as CF 2 –O and CF 2 –S. 7 In sharp contrast, the direct synthesis of the CF 2 –N unit is relatively less explored, probably because of its low stability.…”

“…Alternatively, the dehalogenative azidation of alkyl halides with ethanesulfonylazide via a radical pathway has emerged as a useful access to alkylazides, unfortunately, this approach is only limited to the secondary substrates. 19 During our continuing interest in the chemistry of di(mono)fluoroalkylation, 6,20 we herein report a radical azidation of iododifluoroketones with the commercially available TMSN 3 under iron catalysis, which is complementary to the aforementioned protocols for the synthesis of α-difluoroalkylazides, and the obtained products could be readily applied in the copper( i )-catalysed azide–alkyne cycloaddition (CuAAC), affording the structurally valuable triazolyl difluoroketones 21 (Scheme 1f). The alkyl radical generated from peroxide initiators enables the XAT (halogen atom transfer) process to produce the difluoroalkyl radical, which undergoes outer-sphere radical azidation to render the otherwise challenging CF 2 –N bond formation under iron catalysis.…”

Semipinacol Rearrangement of Iododifluorohomoallyl Alcohols and Its Application in the Allylic C–H Esterification Reactions

“… Accordingly, tremendous efforts have been made to develop facile access to difluoromethyl ketones . Our research group has been devoting substantial efforts to explore new reactions of fluorine-containing building blocks to realize a series of novel difluoroalkyl reactions and provide new methods for the construction of difluoromethyl ketones …”

Photoinduced selective perfluoroalkylation of terminal alkynes via electron donor–acceptor complexes

“…Later on, transition-metal 5 or visible-light-induced 6 perfluoroalkylation of terminal alkenes to form C(sp)–R F bonds based on the radical addition/reduction elimination process was developed (Scheme 1a). On the other hand, the addition of halo-fluoroalkanes to alkynes via the atom transfer radical addition (ATRA) strategy enabled by transition-metal 7 or photocatalysts 8 has also been developed as an attractive methodology for the synthesis of fluoroalkylated alkenes (Scheme 1a). Nevertheless, the protocols mentioned above are usually performed with transition metals, photocatalysts, or radical initiators.…”