Fe-Catalyzed Radical Trifluoromethyl-Alkenylation of Alkenes or Alkynes with 2-Amino-1,4-naphthoquinones

Abstract

The first Fe-catalyzed three-component radical trifluoromethyl-alkenylation of alkenes with 2-amino-1,4-naphthoquinones and CF3SO2Na is reported. The developed reaction enables the highly regioselective preparation of a variety of valuable CF3-substituted 1,4-naphthoquinones in acceptable yields. In the light of the catalytic system, alkynes smoothly afford the corresponding three- or four-component trifluoromethyl-alkenylation products. This protocol features use of easily available and inexpensive reagents, broad substrate scope, and simple reaction conditions.

Carbotrifluoromethylations of C−C Multiple Bonds (Excluding Aryl‐ and Alkynyltrifluoromethylations)

“…Furthermore, the employment of the same 1,4‐naphthoquinone substrates in trifluoromethyl‐alkenylation reaction was reported recently by Tang [31] and co‐workers. In this procedure, Langlois’ reagent was applied as the CF 3 source, FeSO 4 ⋅7H 2 O as the catalyst, and K 2 S 2 O 8 as the oxidant providing the corresponding products in moderate to good yields (Scheme 20b).…”

“…In contrast, there is only a single publication in the literature regarding the functionalization of the carbon‐carbon triple bond. Very recently, Tang [31] et al. reported the iron‐catalyzed radical trifluomethyl‐alkenylation reaction of alkenes with 2‐amino‐1,4‐naphtoquinones using Langlois’ reagent, described above.…”

“…The difunctionalization of the carbon-carbon triple bond toward alkyltrifluoromethylation has received increased attention in organic syntheses in the last few years. In contrast to the single alkenyltrifluoromethylation reaction of alkynes reported recently by Tang 31 , there are a few methodologies for the synthesis of alkyltrifluoromethylated derivatives. The majority of these protocols are bistrifluoromethylation reactions.…”

Langlois Reagent: An Efficient Trifluoromethylation Reagent

“…This method has been displayed as high regioselectivity and functional group tolerance. 14 Behera and co-workers developed an efficient and scalable protocol for the synthesis of trifluoromethylated chromones from readily accessible o-hydroxyphenyl enaminones. The transformation is affected by the Langolis reagent in DMSO with a catalytic amount of Cu(OAc)2, and TBHP oxidant at room temperature.…”

tert-Butylhydroperoxide mediated radical cyanoalkylation/cyanoalkenylation of 2-anilino-1,4-naphthoquinones with vinylarenes/arylalkynes and azobis(alkylcarbonitrile)s

“…7 Tang et al reported three-component trifluoromethyl alkylation and alkenylation reactions with 2-aminonaphthoquinones by using alkenes and alkynes as intermediary radical acceptors. 8…”