title: Syntheses and structures of isomeric [6.6]- and [8.8]cyclophanes with 1,4-dioxabut-2-yne and 1,6-dioxahexa-2,4-diyne bridges.
abstract: All three isomers (ortho, meta, and para) of [8.8]cyclophane bearing 1,6-dioxahexa-2,4-diyne bridges have been synthesized and structually characterized by single-crystal X-ray crystallography to determine the conformation of the cyclophanes and their cavity dimensions. The three isomeric [6.6]cyclophanes bearing 1,4-dioxabut-2-yne bridges have also been synthesized from but-2-yne-1,4-diol ditosylate and the isomeric dihydroxybenzenes. The [6.6]orthocyclophane has been structurally characterized by single-crystal X-ray crystallography. The energy-minimized structures from the semiempirical AM1 calculations of these cyclophanes compare very well with the structures obtained by X-ray crystallography.
authors.affiliation: Department of Chemistry, Indian Institute of Technology, Madras 600 036, India.
authors.forename: M
authors.initials: M
authors.lastname: Srinivasan
authors.forename: S
authors.initials: S
authors.lastname: Sankararaman
authors.forename: H
authors.initials: H
authors.lastname: Hopf
authors.forename: I
authors.initials: I
authors.lastname: Dix
authors.forename: P G
authors.initials: PG
authors.lastname: Jones