Novel chiral stationary phases comprising 2,4-(or 2,6)-diamino-5,6-(or 2,5)-dichlorobenzene-1,3-dicarbonitrile and 1-acyl (1R,2R)-diaminocyclohexane

Novel chiral selectors 3-5 were prepared by regioselective nucleophilic sub stitution of 2,4,5,6-tetrachlorobenzene-1,3-dicarbonitrile (TCBDC, 1) at C( 4) by (1R,2R)-trans-diaminocyclohexane, followed by acylation of the interm ediary 2 with carboxylic acids containing pi -acid or pi -basic unit. On su bstitution of the second chlorine atom by the spacer 3-aminopropyltriethoxy -silane (APTES), a 1 : 1 mixture of regioisomers of N-({[3, 6-dichloro-2,4- dicyano-5-(4,4,4-triethoxy-4-silabutyl)-amino]phenyl}amino)cyclo-hexylcarbo xamides and N-(5,6-dichloro-2,4-dicyano-3-(4,4,4-triethoxy-4-silabutyl)-ami no] phenyl}amino)cyclohexylcarboxamides (6/7, 8/9, 10/11) was obtained. The ir covalent binding to Nucleosil 100-5 provided three new chiral stationary phases (CSP-1-CSP-3). NMR spectra of model compounds 12-14 and MM2 calcula tions on model compounds 15,16 revealed pi-pi interactions between persubst ituted benzene ring and second aromatic ring. The results of the evaluation of new CSPs in the separation of 23 test racemates by HPLC are reported. C SP-2 and CSP-3, that have lower conformational freedom than CSP-1, allow fo r better separation. In particular, good results are obtained In the separa tion of some 1,4-benzodiazepines and open-chain aromatic amides by CSP-2 an d CSP-3.