Molecular recognition of xanthine alkaloids: First synthetic receptors fortheobromine and a series of new receptors for caffeine

Synthetic receptors (H3, H4, H5 and H6) are designed and synthesised for th e first time for theobromine, a xanthine alkaloid used as a diuretic. The s ynthesis of the receptor H6 is achieved by Co(PPh3)(3)Cl-mediated homocoupi ng of 3-(ethoxycarbonyl)benzyl bromide 12 under mild conditions. New caffei ne receptors (H7, H8 and H9) are designed and synthesised. The binding resu lts of theobromine and caffeine (both by NMR and UV studies) are reported.