Reactivity of 3,3,3‐Trifluoropropyne at Rhodium Complexes: Development of Hydroboration Reactions

Abstract

The rhodium compounds [Rh(C≡CCF )(PEt ) ] (2), fac-[RhH(C≡CCF ) (PEt ) ] (3), and fac-[Rh{(E)-CH=CHCF }(C≡CCF ) (PEt ) ] (4) were synthesized by reactions of the rhodium(I) complexes [Rh(H)(PEt ) ] (1) and [Rh(Bpin)(PEt ) ] (5, HBpin=pinacolborane) with the alkyne 3,3,3-trifluoropropyne. Reactivity studies of [Rh(C≡CCF )(PEt ) ] (2) were performed with CO and CO to form [Rh(C≡CCF )(CO)(PEt ) ] (7) and subsequently trans-[Rh(C≡CCF )(CO)(PEt ) ] (8) as well as the labeled derivatives. Using 1-4 as catalysts, hydroboration reactions selectively afforded borylated building blocks.

Overview of Regioselective and Stereoselective Catalytic Hydroboration of Alkynes

“…Subsequently, Suzuki cross‐coupling of multi‐alkenylborane compounds led to a variety of substrates containing chromophore units to yield fluorescent dye‐substituted products. Given the importance, further studies on Rh‐catalytic systems for stereoselective hydroboration of alkynes were carried out, [34,35] showing that a rhodium hydride species could efficiently catalyze the selective hydroboration of 3,3,3‐trifluoroprop‐1‐yne to produce E‐ selective product 15 (Scheme 4d) [35] …”

A SF5 Derivative of Triphenylphosphine as an Electron-Poor Ligand Precursor for Rh and Ir Complexes

“…The 31 P{ 1 H} NMR spectrum for the mixture of complexes 7′ and 8′ showed the two resonances at δ 3.52 and 0.84 ppm as a doublet ( 2 J P-C = 13.7 Hz) and a triplet ( 2 J P-C = 13.5 Hz), respectively. Note that the values of the carbon-phosphorus coupling constants are consistent with cis arrangements [ 64 , 65 ]. On the other hand, in the 13 C{ 1 H} NMR spectrum a doublet ( δ = 175.6 ppm, complex 7′ ) and a triplet ( δ = 179.6 ppm, complex 8′ ) with similar coupling constants are observed for the carbonyl ligands.…”

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

“…64 Though, treatment of [Rh(F)(PEt 3 ) 2 ] 2 (14b) 65 with two equivalents of 3,3,3-triuoropropyne led to a mixture of products where only [Rh(H)(C^CCF 3 ) 2 (PEt 3 ) 3 ] and [Rh{(E)-CH]CHCF 3 }(C^CCF 3 ) 2 (PEt 3 ) 3 ] were identied. 43 Similarly, the use of phenylacetylene or penta-uorophenylacetylene did not provide any vinylidene complex.…”

“…A reaction of [Rh(H)(PEt 3 ) 3 ] (1) with Z -1,3,3,3-tetrafluoropropene resulted after 30 minutes in the formation of a mixture of the complexes [Rh{( E )-CH CHCF 3 }(PEt 3 ) 3 ] (2), 24 [Rh{( E )-CF CHCF 3) }(PEt 3 ) 3 ] (3), [Rh{( Z )-CH CHCF 3 }(PEt 3 ) 3 ] (4) and [Rh{F(HF) 2 )}(PEt 3 ) 3 ] (5) 41,42 in a 3.8 : 2 : 1 : 4.4 ratio, as well as the release of 3,3,3-trifluoropropene ( Scheme 1 ). After 5 hours complex 2 was completely consumed, while higher amounts of the complexes 3 and 5 were obtained; and the formation of the rhodium( i ) alkynyl complex [Rh(C CCF 3 )(PEt 3 ) 3 ] (6) 43 was also observed. After one day, the complexes 5 and 6 were detected in a 1 : 1 ratio ( Scheme 1 ).…”