Vicinal tetrahydrofuran polysubstitution of simulated fatty acids

Selective lithium ion binding involving inositol-based tris(spirotetrahydrofuranyl) ionophores: formation of a rodlike supramolecular ionic polymer from a homoditopic dimer

The stereoselective replacement of all three hydroxyl groups in myo-inositol orthoformate by spirotetrahydrofuran rings in that manner which projects the C--O bonds in the molecular interior has been examined. The heterocyclic components were introduced sequentially, a protocol that demonstrated the utility of precomplexation to LiClO(4) as a stereocontrol tactic. The capability of 3 to coordinate to alkali metal ions was quantified. The conformationally restricted nature of this ligand conveys high selectivity for binding to lithium ion. Beyond that, the ionophore prefers to form 2:1 complexes with Li(+) and exhibits little tendency for 1:1 stoichiometry. These properties are shared by the "dimer" 36, in which two building blocks of type 3 have been conjoined by a 1,3-butadiyne tether positioned at the ortho ester terminus. This bifacial ligand reacts with one equivalent of LiClO(4) or LiBF(4) to form rodlike ionic polymers. Alternative recourse to lithium picrate results in production of the doubly capped homoditopic complex 41. Various other aspects of the chemistry peculiar to these systems are discussed.

Vicinal tetrahydrofuranyl substitution of alkyl chains. Tetra-, penta-, and hexafunctionalized arrays

The tetrakis (tetrahydrofuranyl) dialdehydes 14 and 19 are accessible by oxidative cleavage of extensively substituted cyclohexenes, which have in turn been assembled in a stereocontrolled manner. Reaction of 14 with an excess of the Normant reagent followed by ring closure resulted in conversion to the hexafunctionalized polyether 15. Allylindation of the same dialdehyde gave rise to lactol 16, a reactivity pattern that was essentially duplicated when 19 was treated with the Normant reagent. Attempts to add allylmagnesium bromide to 19 resulted in operation of a Tishchenko reaction with formation of lactone 23. By means of X-ray diffraction analysis, it was possible to ascertain the conformation adopted by 20 and 23 in the solid state. In addition, 15 was shown to populate a conformation in which the oxygen are very predominantly in gauche arrangements, this structural preorganization taking place in the absence of any metal ions.

Diastereoselective two-directional synthesis and cation transport ability of the central tristetrahydrofuranyl unit of meso polyether glabrescol as naturally occurring podand

The diastereoselective synthesis of the central 2,5-linked tristetrahydrofuran (trisTHF) 6 of naturally occurring meso polyether, glabrescol (5), has been achieved in a two-directional manner by the vanadium(V)-catalyzed anti oxidative cyclizations of diol 14. The trisTHF podand 6 and its stereoisomeric analogs 7 and 8 exhibited outstanding cation transport abilities for physiologically important Na+ and K+.