Alkyne-enol ether cross-metathesis in the presence of CuSO4: Direct formation of 3-substituted crotonaldehydes in aqueous medium

An efficient synthesis of 3-substituted crotonaldehydes via alkyne-enol ether cross-metathesis in the presence of CuSO4 and in aqueous medium was developed. Crotonaldehydes were obtained in good yields from terminal aryl-alkynes as well as from terminal alkyl-alkynes. All of the reactions were carried out under microwave irradiation and were completed in a few minutes. Water was used as the cosolvent, making this approach safer, economic, and desiderable from an enviromental point of view.