title: Mechanistic analysis of the photocycloaddition of silyl-tethered alkenes.
abstract: The photochemistry of substituted cinnamyloxy silanes has been examined in both cyclohexane and acetonitrile solvents. Alkene isomerization occurs in addition to cycloaddition. Fluorescence quantum yields and excited singlet state lifetimes have been determined for each compound. We have used the information in order to better understand the regio- and stereoselectivity of photocycloaddition between silyl-tethered cinnamyl groups. This study allows us to conclude that the 2 + 2 photocycloaddition between alkenes is not a Woodward-Hoffmann orbital symmetry controlled event. The most consistent explanation for the excellent regio- and stereoselectivity is that the photocycloaddition is conformationally controlled.
authors.affiliation: Department of Chemistry & Biochemistry, Brigham Young University, Provo, UT 84602, USA. steve_fleming@byu.edu
authors.forename: Steven A
authors.initials: SA
authors.lastname: Fleming
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Parent
authors.forename: Ephraim E
authors.initials: EE
authors.lastname: Parent
authors.forename: James A
authors.initials: JA
authors.lastname: Pincock
authors.forename: Lise
authors.initials: L
authors.lastname: Renault
mesh_terms: D000438:Alcohols / Q000138:chemical synthesis / Q000737:chemistry / Q000528:radiation effects; D000475:Alkenes / Q000737:chemistry* / Q000528:radiation effects; D003500:Cyclization; D015394:Molecular Structure; D010777:Photochemistry; D012821:Silanes / Q000138:chemical synthesis / Q000737:chemistry* / Q000528:radiation effects; D013237:Stereoisomerism; D014466:Ultraviolet Rays
chemical_list: D000438:Alcohols; D000475:Alkenes; D012821:Silanes