title: Diastereoselective lower rim (1S)-camphorsulfonylation as the shortest way to the inherently chiral calix[4]arene.
abstract: [structure: see text]. A diastereomeric mixture of chiral 25-(1S)-camphorsulfonyloxy-26-isopropoxycalix[4]arene 2a (de 15%) and 25-isopropoxy-26-((1S)-10-camphorsulfonyl)calix[4]arene 2b has been obtained by asymmetrical lower rim (1S)-camphorsulfonylation of the monoisopropoxycalix[4]arene. Pure diastereomer 2a has been obtained by simple crystallization, and its absolute configuration has been determinated by X-ray analysis. Enantiomerically pure inherently chiral 5,11-dibromo-26-isopropoxycalix[4]arene 4 has been synthesized by the upper rim dibromination of the diastereomer 2a followed by hydrolytical removal of the auxiliary camphorsulfonyl group.
authors.affiliation: Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Murmanska Str 5, 02660 Kyiv-94, Ukraine.
authors.forename: Anton V
authors.initials: AV
authors.lastname: Yakovenko
authors.forename: Vyacheslav I
authors.initials: VI
authors.lastname: Boyko
authors.forename: Oksana
authors.initials: O
authors.lastname: Danylyuk
authors.forename: Kinga
authors.initials: K
authors.lastname: Suwinska
authors.forename: Janusz
authors.initials: J
authors.lastname: Lipkowski
authors.forename: Vitaly I
authors.initials: VI
authors.lastname: Kalchenko