1. Creation of the bioactive molecules
Our interest is aimed at the creation of bioactive molecules based on organic synthesis, structure analysis and modification of natural products. We believe that the combination of total synthesis and computer chemistry that enables a search of transition states, prediction of spectroscopic data and comprehensive conformational analysis can realize the establishment of the concise synthetic route to complex compounds, structure assignment of rare natural products and rational design of the natural product-mimicking molecules. Toward the post natural product synthesis, we are working on the computer-aided synthetic chemistry.
2. Structural Analysis of Woody Biomass and Its Conversion into Useful Chemicals
Ball-milled wood powder can be dissolved in ionic liquid at moderate temperature without severe modification of its comonents, including lignin, hemicellulose and cellulose. Our research projects are the structural analysis of biomass components dissolved in ionic liquid by usingn HSQC NMR spectra and the conversion of the dissolved wood components into useful chemicals. Microwave heating is also applied to the conversion in ionic liquid.
Lignin is a complicated biomacromolecule in plant cell walls. Among the various substructures in lignin, β-O-4 structure is the most important substructure. Some herbaceous plants such as abaca and kenaf contain β-O-4 rich lignin. The frequency of the β-O-4 structure reaches more than 80%. Such lignins are acylated at γ-position and are thought to be made from radical coupling of monolignol acetate and p-coumarate. Our goal is to elucidate radical coupling mechanism of monolignols to affect the frequency of β-O-4 structure. We also developed the facile synthetic methods for artificial lignin polymer composed only of β -O-4 structure and the polymer is used as lignin model compound.