A wide range of commercially available aldehydes have been applied to Knoevenagel condensation reaction to give E-alkenylphosphine oxides and vinylphosphine oxides. The readily available phosphinoylacetic acids derived from P(O)–H compounds were used as the starting materials in the reaction, providing a highly stereoselective and efficient method for constructing α,β-unsaturated phosphine oxides. Moreover, this simple and practical procedure provides an alternative and more environmentally friendly synthesis strategy for this type of P-functionalized alkenyl compounds.
Key words
Knoevenagel condensation - alkenylphosphine oxide - phosphinoylacetic acid - amine/acid-catalyzed - metal free