Stereoselective synthesis and structure of new types of calix[4] resorcinarenes.: Complexation of tetrakis(O,O-phosphorus)-bridged-calix[4]resorcinarenes with heavy metal atoms

The acid-catalyzed (with HCl) condensation reactions of resorcinol (1) with 1-naphthaldehyde (2) and isobutyraldehyde (3) furnished the tetrameric macrocyclic compounds 4 and 6. Detailed NMR-investigations of the acetylated tetrameric species 5 surprisingly support a structure not in agreement with the expected all-cis conformation. The chair conformation (C-2h symmetry) of the acetylated derivative 5 was established through a crystal X-ray diffraction study. The naphthyl substituents are arranged in trans position above and below the plant made up by the resorcinol units. The reaction of resorcinol 1 with isobutyaldehyde, in accord with expectation, led to the calix[4]resorcinaren (6). The H-1 NMR spectra of compound 6 and 7 appeared at room temperature as broad signals, indicating a conformation of Ct, symmetry The reaction of the C-methyl-tetrakis-P-(chlorodioxaphosphocin)-calix[4]resorcinarenes (8) and (10) with suitable N-trimethylsilyl organic amines were conducted in tetrahydrofuran suspension, furnishing the P-N-substituted calix[4]resorcinarenes (9) and (11). While in the complexation of C-methyl-tetrabromotetrakis-P-(dimethylaminodioxaphosphocin)-calix[4]resorcinarene (13) with (tht)AuCl (tht = tetrahydrothiophene) the expected, neutral tetra-substituted complex 15 was formed, the reaction of 13 with moist acetonitrile led to the anionic atomic framework 14. X-ray structure determinations of the complexes 14 and 15 show that both possess the cone conformation. In the gold complex 151 the Au-CI groups form a loose aggregate, with three Au Cl contacts of 316-340 pm; one of the groups points towards the centre of the cone. The copper(I) complex 14 displays crystallographic mirror symmetry, with a central Cu-4 Cl-5 unit involving tetrahedrally coordinated copper.