Synthesis and host properties of (1,3)-p-tert- butylcalix[5]crown-6 derivatives incorporating the 1,1 '- binaphthalene-2,2 '-dioxy subunit

Alkylation of p-tert-butylcalix[5] arene (1) with 2,2'-bis(5-tosyloxy-3-oxa-1-pentyloxy) 1,1'-binaphthalene ((+/-)-2) in the presence of CsF affords selectively racemic 1,3-bridged calix[ 5] crown-6-triol 3, along with very small amounts of the (1, 2)-bridged regioisomer 4. Compound 3 has been converted into tri-methoxy and tri-alpha-picolyloxy derivatives 5 and 6, respectively, by exhaustive alkylation with the appropriate electrophile and base. The direct separation of the enantiomers of racemates 3 and 6 was achieved by HPLC, using a chiral stationary phase (Chiralpak AD). Hosts 5 and 6 are able to selectively form 1 : 1 endo-cavity complexes with the linear RNH3+ ions.