TETRAHEDRON: ASYMMETRY Tetrahedron: Asymmetry 13 (2002) 1231–1236 Pergamon Preparation, structural and conformational study of cyclobis[(R,R )-,-bis(trifluoromethyl)- 9,10-anthracenedimethylsulphite] M. Sa ´nchez-Aris, a I. Maestre, a T. Parella, a C. Jaime, a A. Virgili, a, * A. Alvarez-Larena b and J. F. Piniella b a Departament de Quı ´mica, Universitat Auto `noma de Barcelona, 08193 Bellaterra, Barcelona, Spain b Departament de Geologia, Universitat Auto `noma de Barcelona, 08193 Bellaterra, Barcelona, Spain Accepted 31 May 2002 Abstract—The macrocycle cyclobis[(R,R )-,-bis(trifluoromethyl)-9,10-anthracenedimethylsulphite) has been prepared and the two possible arrangements have been identified and are described. A conformational study was carried out using NMR and molecular modelling techniques and X-ray diffraction analysis has allowed full assignment of the crystal structure. © 2002 Elsevier Science Ltd. All rights reserved. 1. Introduction The identification and quantification of enantiomeric mixtures is an important part of the analysis of organic compounds. The use of NMR with the aid of chiral auxiliaries, such as chiral solvating agents (CSAs), is an essential methodology in organic chemistry and consti- tutes one of the most useful and frequently employed methods to determine the composition of enantiomeric mixtures. The search for new, highly effective and universal CSAs is a very important research target within this field. Moreover, the complex of a chiral substrate with a CSA constitutes a simple model for receptor–substrate interactions where the chirality of the substrate is one of the most important selection factors. Recently, we presented the preparation and the study of ,-bis(trifluoromethyl)-9,10-anthracenedimethanol 1, 1 which, in enantiomerically pure form, behaves as a very effective CSA. The presence of two chemical functional- ities increases the discrimination between the enan- tiomers, possibly as a result of geometric factors that also modify the kinetics of the process. The formation of an association complex, where enantiodifferentiation originates, could be favoured if a host–guest complex is formed. The difunctional compound 1 represents a good starting point to build chiral macrocycles that can lead to stable associations and thus allow chiral recognition. Anthracenophanes are cyclophanes containing anthra- cene rings. Most of them are connected at the 9 and 10 positions. The ([2,2](9,10)-anthracenophane), the sim- plest homologue, is obtained 2 by dimerization of 9,10- di(chloromethyl)anthracene. Some researchers 3 have combined anthracene rings with ether bonds giving cyclophane-crown ether hybrid macrocycles. Disulphide and disulphone derivatives 4 are used as precursors for 9,10-dihydro-9,10-dimethyleneanthracene. The anthra- cene ring can also be used 5 as a spacer that determines the length of the macrocycle. We have published 6 the preparation and structural study of di[(S )-1-(9-anthryl)-2,2,2-trifluoroethyl]sulphite where the perpendicular disposition of the anthracene rings was demonstrated, giving an attractive intramolecular edge-to-face aromatic interaction. 7 Herein, we present the preparation and structural study of similar regioisomeric macrocyclic derivatives of 1. * Corresponding author. E-mail: albert.virgili@uab.es 0957-4166/02/$ - see front matter © 2002 Elsevier Science Ltd. All rights reserved. PII:S0957-4166(02)00265-3