Cyclopropanation with Fischer acyloxycarbene complexes: preparation of cyclopropane and cycloheptane-fused gamma-lactones.
[reaction: see text] A sequential acylation-intramolecular cyclopropanation reaction takes place upon treatment of a series of tetraalkylammonium acylchromates with beta,gamma-unsaturated acyl chlorides at -10 degrees C. The reaction leads to 2-oxabicyclo[3.1.0]hexan-3-ones with exo selectivity in good yields. The diastereoselectivity of the reaction allows the preparation of cis-divinyl cyclopropanes, which evolve via Cope sigmatropic reaction toward cycloheptadiene derivatives. Furthermore, the aromatic Cope rearrangement of a series of cis-aryl vinyl cyclopropanes prepared by means of this methodology has been studied.
Barluenga
Jose
J
Instituto Universitario de Química Organometálica Enrique Moles, Universidad de Oviedo, Unidad asociada al C.S.I.C., Julián Clavería 8, Spain. barluenga@sauron.quimica.uniovi.es
Aznar
Fernando
F
Gutiérrez
Ignacio
I
Martín
J Alfredo
JA