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The facile preparation of a C 4 -symmteric tetratriazolium salt and its subsequent metalation to generate a series of tetranuclear mesoionic carbene gold(I) complexes is presented. The complete structural characterization of the metallic carbenes and the benefits of cooperative catalysis in the processes of hydroamination and hydrohydrazination of terminal alkynes are discussed.

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W e have prepared two new tetracyclic phenylboronic esters 4 and 5 derived from myo-inositol and from 1,2-0-isopropylider;~e-myo-inositol, respectively. The structures of these compounds were established from NMR and IR spectra, elemental analyses, and an Xray INTROD UCTI0.NWe are involved in the study of organic boron derivatives of cyclitols principally derived from bi-"To whom correspondence should be addressed.ologically active molecules such as quinic acid 121. The study of the reactivity of polyfunctional organic molecules toward the boron reagents affords relevant information about the structures. In addition, the possibility of introducing several boron atoms in a small organic molecule could be of interest in the search for boron targets for neutron cancer therapy. We are also interested in the electronic behavior of boron and in knowing how coordination or retrocoordination may stabilize new structures [3].Myo-inositol 1 is a very important biological substance involved in several cell functions and its derivatives are being actively studied [4]. Compound 1 contains a cyclohexane ring with six hydroxy groups. Its preferred conformation has five equatorial oxygen atoms and one axial oxygen [SI.The polyfunctional character of 1 makes it possible to obtain several polycyclic compounds by reaction with phenylboronic acid. One, two, or three boronate groups can be introduced.Reaction of 1 with 2,2-dimethoxypropane affords selectively compound 2 showing that the equatorial and axial hydroxy groups (C-1 and C-2 or C-2 and C-3) are more reactive than the other groups [61. Under stronger acidic conditions, a second compound 3, among others, can be obtained corresponding to a second dioxolane ring bridging C-4 and C-5. In both dioxolane derivatives, the cyclohexane conformation is the same as in 1 [7].We were interested in investigating the reaction of 1 with different amounts of phenylboronic acid in order to see if it followed the same behavior as that observed in the dioxolane formation and whether it was possible to obtain products with 0 1994 VCH Publishers, Inc