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Agenda de l'ENS de Lyon

Hexafluoroisopropanol as a Versatile Solvent for Selective Catalytic Reactions of Alkenes to Amines

Date
mar 25 oct 2021
Horaires

10H00

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Soutenance de thèse de M. PENG Gongming sous la Direction de M. Marc Pera-Titus

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Description générale

In this thesis, we investigated the use of hexafluoroisopropanol (HFIP) as solvent for selective catalytic reactions of alkenes to amines. First, we studied the catalytic hydroarylation of non-activated alkenes with aniline, aiming at preparing C-functionalized aniline derivatives as precursors for manufacturing polyurethanes. The combination of Bi(OTf)3 and HFIP promoted the hydroarylation of various non-activated alkenes with aniline at with high yield (71%-92%). Catalytic experiments supported by DFT calculations suggest that the true catalytic species is triflic acid (TfOH) generated by hydrolysis of Bi(OTf)3, and that the promoting effect of HFIP is due to stabilization of the rate-determining transition state trough H-bonding interaction between triflate anions and HFIP.
Next, we studied the room-temperature transformation of olefins with formaldehyde to α,β-unsaturated aldehydes using N,N-dimethylamine (DMA) as organocatalyst and HFIP-water as solvent. The reaction proceeds via a domino imino-ene / hydride transfer / aldol condensation pathway. At optimized conditions, 80% yield of α,β-unsaturated aldehydes was achieved at full olefin conversion for a broad scope of substrates using a catalytic amount of DMA. 
In the above transformation, imino-ions can add to olefins via imine-ene / 1,5-hydride transfer and hydrolysis generating long-chain secondary amines as by-products. In this route, we found that HCOOH can act as hydride source to reduce the imino-ion into aliphatic tertiary amines with 33-87% yield using aliphatic olefins and DMA as reactants.
 

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