title: Synthesis, stereochemistry, and photochemical and thermal behaviour of bis-tert-butyl substituted overcrowded alkenes.
abstract: In order to study the structural limits in the design of molecular motors, a tert-butyl substituted analogue was prepared. The unexpected photochemical and thermal isomerisation processes and the stereochemistry of new overcrowded alkene are described. The bis tert-butyl substituted alkenes were synthesised in a five-step sequence with an overall yield of 7.5%. Structural assignments of the isomers based on experimental data were supported by calculations of all four isomers of the alkene. X-Ray crystal analysis showed a strongly twisted alkene (torsion angle 39 degrees ) for a less stable photochemically generated cis-isomer.
authors.affiliation: Department of Organic and Molecular Inorganic Chemistry, Stratingh Institute, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands.
authors.forename: Matthijs K J
authors.initials: MK
authors.lastname: Ter Wiel
authors.forename: Marcin G
authors.initials: MG
authors.lastname: Kwit
authors.forename: Auke
authors.initials: A
authors.lastname: Meetsma
authors.forename: Ben L
authors.initials: BL
authors.lastname: Feringa