Desymmetrization of symmetric diesters

Developing environmentally friendly, cost-effective, synthetic methodologies has been of central importance for synthesis of a variety of compounds in both academia and industry. Desymmetrization of symmetric compounds is one of the most effective ways because the starting symmetric compounds are typically obtained easily on a large scale starting from inexpensive sources. In this research area, we developed non-enzymatic reactions that enable desymetrization of symmetric diesters by monohydrolysis of two identical ester groups. Before this discovery, such reactions were considered possible only by enzymes, which provide no basis for predictions for reactivities. However, Niwayama discovered a highly efficient and practical ester monohydrolysis of symmetric diesters (Scheme 1), employing a THF-water medium at 0oC. Using this reaction, a number of pure half-esters have been obtained in high yields to quantitative yields in a very straightforward manner.

Since the reaction conditions are quite mild and simple, the synthetic utility of this reaction is expected. To our knowledge, this finding is the first example of systematic studies of non-enzymatic monohydrolysis reactions of symmetric diesters. This work was featured in an article in Chemical Process Development in Chemical and Engineering News (2001, January 22, p92-94). This research area has potential in many points of view, such as synthetic organic chemistry, theoretical chemistry, physicochemical, medicinal chemistry. We are currently expanding the scope of this reaction by mechanistic studies, development of asymmetric versions, and syntheses of bioactive compounds, etc.

Development of a proteomic methodology for quantitative protein/peptide analysis

Proteomics, analysis of sets of proteins expressed by a cell, tissue, or organism under specific conditions, is a newly emerging field in the postgenomics era, and is rapidly becoming an important research area for studyingthe global events occurring within a cell under certain physiological conditions.

Quantitative measurement of a specific protein within a crude protein mixture is essential for proteomics research. We have developed a methodology for quantification of proteins/peptides by introducing a combination of isotope-labeled/unlabeled small organic molecules that specifically react with cysteine residues of peptides/proteins followed by mass spectrum analysis (MALDI-TOF). Since isotope-labeled and unlabeled compounds are expected to show identical chemical and physical behaviors, and hence identical ionization efficiencies, relative intensities of these peptides reacted with isotope-labeled and unlabeled modifiers are anticipated to reflect relative quantities of (tryptic) peptides and thus the original proteins.

Since mass spectrometry allows identification of proteins by peptide mass fingerprinting, this method is expected to serve as a useful tool for quantifying peptides/proteins for proteomics research. The following scheme shows our methods.