Synthesis of tri-substituted, aliphatic and ¹³C-labelled α,β-unsaturated carboxylic acids via Wittig CO₂ utilisation...

Phosphonium carboxylate ylides are formed through CO₂ activation by phosphonium ylides. These can undergo Wittig reactions with carbonyl compounds, thereby enabling formation of both the C-CO₂ bond and the two bonds of the CC double bond of an α,β-unsaturated carboxylic acid in a one-pot transformation. In this work, we have developed methodology to enable the synthesis of very useful trisubstituted alkene-containing products. Secondly, the protocol allows for the use of base-sensitive aliphatic aldehydes, avoiding the occurrence of aldol self-condensation. Thirdly, we show that this methodology enables production of a labelled α,β-unsaturated carboxylic acid using ¹³C-labelled CO₂.