title: Chemistry of 1-fluoro-2,3,4-triphenylcyclobutadiene dimers.
abstract: The reaction of 2,4-dichloro-1,1-difluoro-3-phenyl-2-cyclobutene 1 with excess phenyllithium and subsequent transformations of the products have been reinvestigated. The phenyllithium reaction appears to proceed through the intermediacy of a fluorotriphenylcyclobutadiene 2 to produce a well-characterized dimeric trans-hexaphenyldifluorotricyclooctadiene 3a. Subsequent transformations of 3a gave a pentaphenyldihydrodifluoropentalene 4, which on acid hydrolysis formed a pentaphenyldihydropentalenone 5. When 3a was photolyzed in benzene, after purification, it afforded 6, an isomer of 5, probably by way of 7, an isomer of 4. Thermolysis of 3a also provided, in low yield, a substance believed to be a pentaphenylfluorophenanthrene 8. Along with isolation of 3a, and probably arising from a different isomer of the 3 family, was a pentaphenylfluorophenanthrene 9, which was suspected of being an isomer of 8. Single-crystal X-ray studies were used to derive structures for 4, 5, 6, and 9. Formation of the unusual and intriguing transformation products has at least been rationalized.
authors.affiliation: Solid State & Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India.
authors.forename: Angshuman R
authors.initials: AR
authors.lastname: Choudhury
authors.forename: Deepak
authors.initials: D
authors.lastname: Chopra
authors.forename: Tayur N Guru
authors.initials: TN
authors.lastname: Row
authors.forename: Kuppuswamy
authors.initials: K
authors.lastname: Nagarajan
authors.forename: John D
authors.initials: JD
authors.lastname: Roberts