| Budget Amount *help |
¥3,900,000 (Direct Cost: ¥3,900,000)
Fiscal Year 2000: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1999: ¥3,100,000 (Direct Cost: ¥3,100,000)
|
|---|
| Research Abstract |
Tellurium atom of tricoordinated tellurium compounds, such as telluroxides, possessing different substituents is chiral, and hence two enantiomers of telluroxides should be resolved and isolated. However, the isolation of optically active telluroxides is known to be quite difficult since the racemization of telluroxides via achiral hydrate by a trace amount of water proceeds very rapidly. It is expected that optically pure telluroxides will be isolated if the telluroxides are kinetically stabilized by bulky substituents and/or thermodynamically stabilized by the coordination of a Lewis base such as amino group on the tellurium atom. 2,4,6-Trimethylphenyl-2'-(N,N-dimethylamino) methylphenyltelluroxide (1), 2,4,6-triisopropylphenyl-2'-(N,N-dimethylamino) methylphenyltelluroxide (2), 2,4,6-tri-tert-butylphenyl-2'-(N,N-dimethylamino)methyl-phenyltelluroxide (3), 8-dimethylamino-1-naphthylphenyltelluroxide (4), and 8-dimethylamino-1-naphthyl-2', 4', 6'-triisopropylphenyltelluroxide (5) were synthesized and optically resolved by chrornatography using an optically active column. Enantiomerically pure compounds of telluroxides (1)-(5) were isolated, and the absolute configurations were estimated by CD spectra in comparison with that of optically pure selenoxide prepared by the independent synthesis and the absolute configuration is known. These optically pure telluroxides were stable in solid state, however, racemized gradually in solutions in spite of water in the solvent was carefully removed. Anyway, we have succeeded to isolate optically pure telluroxides for the first time by stabilizing the telluroxides toward racemization using kinetic and/or thermodynamic stabiliza-tion technique.
|
