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1.  Development of Efficient Cyclization Methods: We are interested in efficient and practical syntheses of cyclic a,b-unsaturated carbonyl compounds that can be served as versatile building blocks for the synthesis of polycyclic natural products.  Efficient synthetic methods for the following compounds have been developed, and the syntheses of polycyclic structures by use of those compounds are under investigation.

1)  Cyclohexenones
2)  Cyclopentenones
3)  Cycloalkene-1-carboxaldehydes
4)  Bicyclo[3.3.1]nonanes
5)  D1-3-Octalones 

 

2.  Chemistry of Isoprenoid:  Isoprenoid can be classified into Terpenoid, Carotenoid, and Steroid.  We have developed various di-functionalized C5 prenyl units that can be efficiently used in chain-extension processes for making various Isoprenoid compounds.  We adopted Julia Sulfone protocol in C-C bond formation, which would give polyprenyl or polyene structures depending on the sulfone elimination process.  Carotenoid natural products have been nicely assembled by use of our C10 di(chloroallylic) sulfide.  We are currently extending this strategy to make other important carotenoid compounds.  After finishing up the synthesis of carotenoid compounds, we will further pursue the synthesis of terpenoid and steroid compound by combined use of our cyclization and chain-extension strategies.  Followings are the carotenoid compounds that we have made or have been making at the present time.

       1) Vitamin A                                  8) Crocetin
       2) Tretinoin                                   9) Nor-Bixin
       3) Isotretinoin                               10) Zeaxanthin
       4) Tocoretinate                             11) Asthaxanthin
       5) b-carotene                               12) Canthaxanthin
       6) Retinyl sulfide                           13) Coenzyme Q-10
       7) Lycopene                                 14) Biotin

 3. Conducting Molecular Wires: Based on our methods of the carotenoid synthesis, we are able to construct the      conjugated polyene chains with variable lengths. This conjugated polyene chains, which conduct electrons, can be      stabilized by attaching phenyl substituents to the chain. We are preparing various organic conducting wires with      different resistances. We are going to build up various paralleled molecular circuits with diverse conductance.