Studies on the reactions of silyl enol ether with perfluoroorganic compounds¹ III. Synthesis of perfluoroalkylated α, β‐unsaturated aldehydes and their derivatives

Abstract

Per‐ and poly‐fluoroalkylated α, β‐unsaturated alkenals were synthesized by the reaction of silyl enol ether of alkanals with per‐ and poly‐fluoroalkyl iodide initiated by Na2S2O4 conveniently in high yield. Their corresponding alkenol and 2,4‐dinitrophenylhydrazone were also synthesized.

Straightforward Synthesis of Fluorinated Enals via Photocatalytic α-Perfluoroalkenylation of Aldehydes

“…During our research, by aiming at perfluoroalkylations of enamines with phosphine EDA complexes, we observed the formation of tetrasubstituted, fluorinated α,β-unsaturated aldehydes. This structural motif is only rarely reported in the literature, − involving mostly the transformation of ketone derivatives. − The recent work by Beller et al provides the first generally applicable method for the synthesis of perfluoroalkenylated ketones (Scheme c) . At elevated temperatures, the addition of an excess of both pyrrolidine and substrate results in the formation of the fluorinated α,β-unsaturated ketones.…”

“…At elevated temperatures, the addition of an excess of both pyrrolidine and substrate results in the formation of the fluorinated α,β-unsaturated ketones. For aldehydes, there are even fewer known protocols that require the intermediate generation of the corresponding silyl enol ether …”

“…For aldehydes, there are even fewer known protocols that require the intermediate generation of the corresponding silyl enol ether. 40 Given the interesting potential of (per)fluorinated enals as synthesis intermediates, an efficient preparation protocol would be desirable, especially with regard to their application in the synthesis of heteroaromatics. 47−49 In this work, we present a straightforward protocol for the photocatalytic transformation of aldehydes into the corresponding β-fluoroβ-fluoroalkylated enals in one step using a simple organocatalyst and triphenylphosphine.…”