title: Pentacyclic laddersiloxane.
abstract: A novel method which effects ring extension of the ladder oligosilsesquioxanes was developed. By applying this method, we synthesized the first functionalized tricyclic laddersiloxanes and pentacyclic laddersiloxane. The reaction of (i-PrSi(OH)O)4 with (i-PrPhClSiO)2 in pyridine gave the tetraphenyl tricyclic laddersiloxane. Following dephenylchlorination with AlCl3/HCl, and hydrolysis enabled us to isolate the tetrahydroxyl tricyclic laddersiloxane in good yield. We repeated the similar reaction from this tetrahydroxyl laddersiloxane, and the first pentacyclic laddersiloxane was obtained. The structures of the tetraphenyl and tetrahydroxyl tricyclic laddersiloxanes, and pentacyclic laddersiloxane were determined by X-ray crystallography.
authors.affiliation: Department of Applied Chemistry, Faculty of Engineering, Gunma University, Kiryu, Gunma 376-8515, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Unno
authors.forename: Akiko
authors.initials: A
authors.lastname: Suto
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Matsumoto