Rhodium‐Catalyzed Addition of Alkynes to Activated Ketones and Aldehydes.

Abstract

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Palladium‐Catalyzed Ring‐Opening Alkynylation of Cyclopropenones

“…In the presence of Pd(PPh 3 ) 4 (5 mol-%) at 40°C in THF, the reaction between 1a and 2a gave alkenyl alkynyl ketone 3aa in 62 % yield, along with diphenylacetylene (15 %) and phenyl phenyl(triphenylphosphoranylidene)methyl ketene (5 %) ( Table 1, Entry 1). [7] The two byproducts, alkyne and ketene, were produced through the decarbonylation of 1a [6e,8] and the ring-opening reaction of 1a with PPh 3 , [9] respectively. To avoid the formation of the undesired phosphane-derived ketene, N-heterocyclic carbenes (NHCs) were employed as ligands for palladium.…”