HFO‐1234yf as a CF 3 ‐Building Block: Synthesis and Chemistry of CF 3 ‐Ynones

Iodonium based regioselective double nucleophilic alkene functionalization of a hydrofluoroolefin scaffold

Herein, we report a modular regioselective alkene difunctionalization strategy based on the use of hydrofluoroolefin (HFO) gas as fluorous feedstock material. The transformation of the HFO gas to iodonium salt creates vicinal electrophilic sites readily available for a broad range of nucleophiles.

Competing C-H and C-F bond activation reactions of a fluorinated olefin at Rh: a fluorido vinylidene complex as an intermediate in an unprecedented dehydrofluorination step

The hydrofluoroolefin Z-1,3,3,3-tetrafluoropropene has been activated via an initial C-F bond activation and subsequent C-H bond activation using [Rh(H)(PEt3)3] (1) or via C-H bond activation at [Rh(CH3)(PEt3)3] (8). In both cases the formation of [Rh{(E)-CF[double bond, length as m-dash]CHCF3}(PEt3)3] (3) was observed. Importantly, the C-F activation product [Rh{(E)-CH[double bond, length as m-dash]CHCF3}(PEt3)3] (2) reacts in the presence of Z-1,3,3,3-tetrafluoropropene into 3. The latter converted into [Rh(C[triple bond, length as m-dash]CCF3)(PEt3)3] (6) by an unprecedented dehydrofluorination reaction, presumably via a vinylidene complex as intermediate. When the carbonyl complex [Rh(C[triple bond, length as m-dash]CCF3)(CO)(PEt3)3] (12) was treated with an excess of NEt3·3HF or HBF4 at low temperature, the formation of the phosphonioalkenyl compounds [Rh{(Z)-C(PEt3)[double bond, length as m-dash]CHCF3}(CO)(PEt3)2]X (X = F(HF) x , BF4) (13) was observed. The formation of 13 can be explained by an attack of PEt3 at the electrophilic α-carbon atom of an intermediate vinylidene complex. The employment of PiPr3 derivatives as model compounds allowed for the isolation of the unique fluorido vinylidene complex trans-[Rh(F)([double bond, length as m-dash]C[double bond, length as m-dash]CHCF3)(PiPr3)2] (16), which in the presence of PEt3 transforms into [Rh(C[triple bond, length as m-dash]CCF3)(PEt3)3] (6).

Application of Industrially Relevant HydroFluoroOlefin (HFO) Gases in Organic Syntheses

Hydrofluoroolefin (HFO) gases are state-of-the-art cooling agents with widespread household and industrial applications. Considering their structural benefits these fluorous feedstocks have gained the attention of organic chemists in the last couple of years. In this short review we summarized the existing synthetic transformations of these gaseous starting material and present their applicability in the synthesis of fluorine-containing organic molecules, which have potential importance as building blocks and reagents for diverse syntheses.

1 Introduction

2 Addition Reactions

3 Substitutions

4 Organometallic Chemistry

4.1 Organolithium Compounds

4.2 Organometallic Complexes

4.3 Silicon Organic Chemistry

4.4 Boron Organic Chemistry

4.5 Palladium-Catalyzed Transformations

4.6 Metathesis

4.7 Hydroesterification, Hydroformylation

5 Conclusions

Continuous flow synthesis of Celecoxib from 2-bromo-3,3,3-trifluoropropene

We describe the total flow synthesis of the widely prescribed anti-inflammatory COX-2 inhibitor Celecoxib from 2-bromo-3,3,3-trifluoropropene, as a convenient and available trifluoromethyl building block, to generate trifluoropropynyl lithium and to trap it immediately with an aldehyde. Oxidation of the obtained alcohol into ketone followed by condensation with 4-sulfamidophenylhydrazine afforded the targeted drug with full regioselectivity. It is noteworthy that the quality of these flow reactions (50% overall yield within 1 h cumulated residence time over 3 steps) directly furnished the target API and intermediates with excellent purity.

Versatile Reaction Pathways of 1,1,3,3,3-Pentafluoropropene at Rh(I) Complexes [Rh(E)(PEt3 )3 ] (E=H, GePh3 , Si(OEt)3 , F, Cl): C-F versus C-H Bond Activation Steps

The reaction of the rhodium(I) complexes [Rh(E)(PEt₃)₃] (E=GePh₃ (1), H (6), F (7)) with 1,1,3,3,3‐pentafluoropropene afforded the defluorinative germylation products Z/E‐2‐(triphenylgermyl)‐1,3,3,3‐tetrafluoropropene and the fluorido complex [Rh(F)(CF₃CHCF₂)(PEt₃)₂] (2) together with the fluorophosphorane E‐(CF₃)CH=CF(PFEt₃). For [Rh(Si(OEt)₃)(PEt₃)₃] (4) the coordination of the fluoroolefin was found to give [Rh{Si(OEt)₃}(CF₃CHCF₂)(PEt₃)₂] (5). Two equivalents of complex 2 reacted further by C−F bond oxidative addition to yield [Rh(CF=CHCF₃)(PEt₃)₂(μ‐F)₃Rh(CF₃CHCF₂)(PEt₃)] (9). The role of the fluorido ligand on the reactivity of complex 2 was assessed by comparison with the analogous chlorido complex. The use of complexes 1, 4 and 6 as catalysts for the derivatization of 1,1,3,3,3‐pentafluoropropene provided products, which were generated by hydrodefluorination, hydrometallation and germylation reactions.

Facile preparation and conversion of 4,4,4-trifluorobut-2-yn-1-ones to aromatic and heteroaromatic compounds

The concise preparation of 4,4,4-trifluorobut-2-yn-1-ones by the oxidation of the readily accessible corresponding propargylic alcohols as well as their utilization as Michael acceptors for the construction of aromatic and heteroaromatic compounds are reported.