Cobalt–Tertiary-Amine-Mediated Hydroxytrifluoromethylation of Alkenes with CF₃Br and Atmospheric Oxygen

Abstract

The mild and efficient hydroxytrifluoromethylation of alkenes with bromotrifluoromethane (CF3Br) and atmospheric oxygen mediated by cobalt-tertiary amine is described. This reaction proceeds with broad substrate scope and good functional group compatibility. Mechanistic studies indicate that the reaction proceeds through a radical pathway, which is enabled by combination of the previously unexplored highly efficient N-isopropyl-N,2-dimethylpropan-2-amine with Co­(II) for the single electron reduction of CF3Br to CF3 radical.

Selective Organic Transformations over Cadmium Sulfide-Based Photocatalysts

“…Additionally, several highly reactive oxygen species, including hydroxyl radical ( • OH), superoxide anion radical ( • O 2 – ), and singlet excited state oxygen ( 1 O 2 ), have been proved to possess the ability to promote oxidation reaction in photocatalysis. − However, the strong oxidation ability of • OH may lead to the nonselective mineralization of organic to small-molecule inorganics instead of selective oxidation of organics into value-added feedstocks . As shown in Figure , because the potential of H 2 O/ • OH is more positive than the VB edge of CdS, the oxidation of H 2 O to • OH on CdS is not thermodynamically feasible, − suggesting that CdS is a promising semiconductor material for the selective transformation of organics.…”

Metal-free photocatalytic intermolecular trifluoromethylation-gem-difluoroallylation of unactivated alkenes

“…Thirdly, a sterically hindered tetrasubstituted alkene ( 4x ) was also compatible with the reaction conditions. 14 Notably, this transformation was found to be successful with both enamide ( 4y ) and enol ether ( 4z , 4aa ), resulting in complete regioselectivity and excellent yields. The operationally simple procedure and absence of transition metals of this reaction provide a practical tool in the late-stage modification of densely functionalized biologically relevant molecules.…”

Visible Light Promotes Cascade Trifluoromethylation/Cyclization, Leading to Trifluoromethylated Polycyclic Quinazolinones, Benzimidazoles and Indoles

“…Screening of the literature shows that CF 3 Br can be reduced to a trifluoromethyl anion via electrochemical reduction [ 30 , 31 ], active metal reduction [ 32 , 33 ], or by P(NEt 2 ) 3 [ 34 ] to react with aldehydes or ketones to give alcohols, or to react with TMSCl to give TMSCF 3 ( Scheme 1 a). Secondly, CF 3 Br can be reduced to a trifluoromethyl radical by Na 2 S 2 O 4 [ 35 ] or the transition metal complex [ 36 , 37 , 38 , 39 ] to couple with aromatic rings or alkenes to give trifluoromethyl compounds ( Scheme 1 b). In 2018, Zhang′s group reported that CF 3 Br could be activated by visible-light catalysis to produce a trifluoromethyl radical and induce a radical addition reaction with alkenes and alkynes ( Scheme 1 c) [ 40 ].…”