title: Photochemical access to tetra- and pentacyclic terpene-like products from R-(+)-sclareolide.
abstract: Fused tetracyclic oxetanes 4, highly substituted cyclobutenes 6, and the pentacyclic derivatives 7 and 8 were obtained by irradiation of derivatives 3 that were prepared from commercial R-(+)-sclareolide (1) in three steps. Compounds 4 are formed through a Paterno-Büchi reaction, while tricyclic derivatives 6 are the fragmentation products of the first formed oxetanes. In clear contrast, cyclopentenyl and 3-furyl derivatives, 3e and 3f, gave the [2+2] adducts, namely pentacyclic derivatives 7 and 8. All the reported reactions are totally regio- and stereoselective, with the exception of the cyclization of furyl derivative 3f, which gave the mixture of both the crossed (7b) and the right (8) isomers.
authors.affiliation: Instituto de Química Orgánica, Consejo Superior de Investigaciones Científicas (CSIC), Juan de la Cierva 3, 28006-Madrid, Spain.
authors.forename: María C
authors.initials: MC
authors.lastname: de la Torre
authors.forename: Isabel
authors.initials: I
authors.lastname: García
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Sierra
mesh_terms: D004224:Diterpenes / Q000138:chemical synthesis*; D007202:Indicators and Reagents; D008958:Models, Molecular; D015394:Molecular Structure; D010777:Photochemistry; D011083:Polycyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism; D013729:Terpenes / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D004224:Diterpenes; D007202:Indicators and Reagents; D011083:Polycyclic Compounds; D013729:Terpenes; C109395:sclareolide