Novel rearrangement of an isocaryolane sesquiterpenoid under mitsunobu conditions
Under modified Mitsunobu reaction conditions, a novel skeleton rearrangement of terpenes has been obtained. The reactivity of 8, 9-dioxygenated isocaryolane derivatives has been investigated. When either (8R,9R)-8-methoxyisocaryolane-9-ol (7) or (8R, 9R)-isocaryolane-8,9-diol (10) are treated under acidic conditions, isocaryolan-9-one (9) and the rearrangement compound (1S,2S,5R,8S)-1, 4,4-trimethyltricyclo[6.2.1.0(2,5)]undecane-8-carbaldehyde (11) are obtained. Otherwise treatment of compounds 7 and 10 under modified Mitsunobu conditions leads to the novel sesquiterpene derivative (1S, 2S,5R,9R)-1,4,4-trimethyltricyclo[7.2.1.0(2,5)]dodecan-8-one (8). This is the first example, to our knowledge, of a Mitsunobu-induced pinacol rearrangement. The influences of the substrate and reaction conditions on the evolution of the reaction are both explored. This modification of the Mitsunobu reaction conditions introduces a new, one-pot, procedure for preparing this class of rearrangement product.
Racero
JC
Departamento de Quimica Organica, Facultad de Ciencias, Universidad de Cadiz, Apartado 40, 11510 Puerto Real, Cadiz, Spain, and The School of Chemistry and Molecular Sciences, University of Sussex, Brighton, BN1 9QJ, Great Britain.
Macias-Sanchez
AJ
Hernandez-Galan
R
Hitchcock
PB
Hanson
JR
Collado
IG