Synthesis of Alkynyl Ketones by Sonogashira Cross-Coupling of Acyl Chlorides with Terminal Alkynes Mediated by Palladium Catalysts Deposited over Donor-Functionalized Silica Gel

Abstract

Palladium catalysts deposited over silica gel bearing simple amine (≡Si(CH₂)₃NH₂) and composite functional amide pendants equipped with various donor groups in the terminal position (≡Si(CH₂)₃NHC(O)CH₂Y, Y = SMe, NMe₂ and PPh₂) were prepared and evaluated in Sonogashira-type cross-coupling of acyl chlorides with terminal alkynes to give 1,3-disubstituted prop-2-yn-1-ones. Generally, the catalysts showed good catalytic activity in the reactions of aroyl chlorides with aryl alkynes under relatively mild reaction conditions even without adding a copper co-catalyst. However, their repeated use was compromised by a significant loss of activity after the first catalytic run.