title: Control of the reversibility during boronic ester formation: application to the construction of ferrocene dimers and trimers.
abstract: Control of the reversibility during boronic ester formation from boronic acids and diols was found to be possible by choosing an appropriate solvent. As an example, ferrocene dimers and trimers were constructed by using tetrol 1 with an indacene framework, 1,1'-ferrocenediboronic acid 2, and ferrocenemonoboronic acid 4. When equimolar amounts of 1 and 2 were mixed in methanol under equilibrating conditions, two kinds of stacked ferrocene dimers homo- and hetero-3 were selectively obtained depending on the reaction time and both structures were determined by X-ray crystallographic analysis. On the other hand, the ferrocene trimer 7 was successfully constructed by stepwise assembly in the presence of anhydrous magnesium sulfate in acetone where the equilibration of boronic esters was suppressed, while no formation of ferrocene trimer 7 was detected when all components 1, 2 and 4 (2 : 1 : 2 ratio) for trimer 7 were mixed at a time in methanol under equilibrating conditions.
authors.affiliation: Department of Chemistry, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro-ku, Tokyo 152-8551, Japan. niwasawa@chem.titech.ac.jp.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Ono
authors.affiliation: Department of Chemistry, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro-ku, Tokyo 152-8551, Japan. niwasawa@chem.titech.ac.jp.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Tohyama
authors.affiliation: Department of Chemistry, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro-ku, Tokyo 152-8551, Japan. niwasawa@chem.titech.ac.jp.
authors.forename: Tatsuhiro
authors.initials: T
authors.lastname: Uchikura
authors.affiliation: Department of Chemistry, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro-ku, Tokyo 152-8551, Japan. niwasawa@chem.titech.ac.jp.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kikuchi
authors.affiliation: Department of Chemistry, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro-ku, Tokyo 152-8551, Japan. niwasawa@chem.titech.ac.jp.
authors.forename: Kotaro
authors.initials: K
authors.lastname: Fujii
authors.affiliation: Department of Chemistry, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro-ku, Tokyo 152-8551, Japan. niwasawa@chem.titech.ac.jp.
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Uekusa
authors.affiliation: Department of Chemistry, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro-ku, Tokyo 152-8551, Japan. niwasawa@chem.titech.ac.jp.
authors.forename: Nobuharu
authors.identifier: http://orcid.org/0000-0001-6323-6588
authors.initials: N
authors.lastname: Iwasawa