(E)-Selective Friedel-Crafts acylation of alkynes to beta-chlorovinyl ketones: defying isomerizations in batch reactions by flow chemistry approaches

Abstract

The Friedel-Crafts acylation of alkynes stereoselectively provides (Z)-beta-chlorovinyl ketones, whereas the AlCl3-promoted reaction yields a mixture of stereoisomeric beta-chlorovinyl ketones. To develop the (E)-selective synthesis of beta-chlorovinyl ketones, a flow chemistry approach was devised for the Friedel-Crafts acylation of alkynes that defies the facile (E). (Z) isomerization under the AlCl3-promoted reaction conditions. Compared to batch reactions, the flow chemistry approach provides a fast, clean, high yielding, and stereoselective synthetic route to (E)-beta-chlorovinyl ketones.