title: A "classical" tetrahydroxycalix[4]arene adopting the 1,2-alternate conformation.
abstract: The first example of a "classical" tetrahydroxycalixarene, which adopts the 1,2-alternate conformation both in solution and in the crystal, is described. Calixarene derivatives with two distal methylene groups substituted in a trans fashion by phenyl (5a) or mesityl (5b) groups were synthesized via addition of PhMgBr/CuCN or MesMgBr/CuCN to the bis(spirodiene) derivative 3. Whereas the phenyl-substituted calixarene derivative 5a adopts the usual "cone" conformation, solution NMR data and X-ray crystallography indicate that the more crowded mesityl derivative 5b adopts a 1,2-alternate conformation with the two mesityl groups located at isoclinal positions of the macrocycle.
authors.affiliation: Department of Organic Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors.forename: Samah
authors.initials: S
authors.lastname: Simaan
authors.forename: Silvio E
authors.initials: SE
authors.lastname: Biali