title: Cycloisomerization of activated (2E,4Z)-heptatrienoate and its relevance to crispatene (bio)synthesis. A case of concerted and stepwise uncertainty.
abstract: A single transition structure was located on the potential energy surface of the cycloisomerization of protic and Lewis acid activated (2E,4Z)-heptatrienal and the corresponding methyl ester to provide the bicyclo[3.1.0]hexene derivatives, the central skeleton of the crispatene natural products. A two-dimensional scan of the C-C bond-forming reactions revealed a barrierless cyclopropane closure following the pentadienyl cycloisomerization, with preservation of the stereochemical information.
authors.affiliation: Departamento de Química Organica, Facultade de Química, Universidade de Vigo, Lagoas Marcosende, E-36310, Vigo, Galicia, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Silva López
authors.forename: Olalla
authors.initials: O
authors.lastname: Nieto Faza
authors.forename: Rosana
authors.initials: R
authors.lastname: Alvarez
authors.forename: Angel R
authors.initials: AR
authors.lastname: de Lera
mesh_terms: D000466:Alkadienes / Q000737:chemistry*; D000475:Alkenes / Q000737:chemistry; D001688:Biological Products / Q000138:chemical synthesis; D001643:Bridged Bicyclo Compounds / Q000097:blood*; D003500:Cyclization; D003521:Cyclopropanes / Q000737:chemistry; D011753:Pyrones / Q000097:blood*; D013237:Stereoisomerism
chemical_list: D000466:Alkadienes; D000475:Alkenes; D001688:Biological Products; D001643:Bridged Bicyclo Compounds; D003521:Cyclopropanes; D011753:Pyrones; C519731:crispatene; C030797:cyclopropane; C117224:1-hexene