title: Gold- and copper-catalyzed cycloisomerizations towards the synthesis of thujopsanone-like compounds.
abstract: In the search for a new access to thujopsanone related compounds by cycloisomerization reactions of unsaturated propargylic alcohols and acetates, we found several interesting reaction types and demonstrated the complementarity of Au, Pt, and Cu catalysts. Thus, 6-en-1-yn-3-ol 10a underwent clean cyclization/ether formation to 16, in particular using Au catalysts (76-98%) or a newly prepared Cu(I)-triflimidate-catalyst (94%). The corresponding acetate 11 a underwent either the cycloisomerization with concomitant [1,2]-acyl shift (to 12: 78% using AuCl(3)) or an unprecedented rearrangement-cycloaddition leading to 20 (43% using [(tBuXPhos)AuNTf(2)]), a strained fused tricyclic ring system containing a [2.2.0] bicyclic subunit.
authors.affiliation: Firmenich SA, Corporate R&D Division, P. O. Box 239, CH-1211 Geneva 8, Switzerland. charles.fehr@firmenich.com
authors.forename: Charles
authors.initials: C
authors.lastname: Fehr
authors.forename: Magali
authors.initials: M
authors.lastname: Vuagnoux
authors.forename: Andrea
authors.initials: A
authors.lastname: Buzas
authors.forename: Jeremy
authors.initials: J
authors.lastname: Arpagaus
authors.forename: Horst
authors.initials: H
authors.lastname: Sommer