Rhodium-catalyzed synthesis of cyclohexenones via a novel [4 + 2] annulation.
[reaction: see text] In the presence of a rhodium catalyst, 4-alkynals react with alkynes to furnish cyclohexenones, presumably via metalacycle 1; as far as we are aware, this is the first example of the generation of this class of compounds through such a transformation. In view of the easy accessibility of 4-alkynals (alkynylmetal + alpha,beta-unsaturated aldehyde) and alkynes, this [4 + 2] cyclization constitutes an interesting new approach to functionalized cyclohexenones.
Tanaka
Ken
K
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Fu
Gregory C
GC