Isomerizations on silica gel: Synthesis of allenyl ketones and the first Nazarov cyclizations of vinyl allenyl ketones

Article abstract of DOI:10.1016/S0040-4039(98)01619-0

Dess-Martin oxidation followed by the chromatographic workup of crude, terminal propargyl ketones 5 on silica gel directly leads to terminal allenyl ketones 6. When the other substituent on 5 was electron-rich, 7 was observed as side-product. If the other substituent on 5 was electron-poor, the isomeric 1-propynyl ketone 8 was the side-product. Chromatography of the crude propargyl vinyl ketones 10 on silica gel delivers the products of a Nazarov cyclization.