Nagasaki University

Department of Chemistry, Nagasaki University, 1-14 Bunkyo-machi. Nagasaki, 852, Japan Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02138, USA To whom correspondence should be addressed. 

Masaaki Kai Department of Medicinal Chemistry, School of Pharmaceutical Sciences, Nagasaki University, Nagasaki, Japan... 

Department of Biochemistry, Nagasaki University School of Medicine, 1-12-4 Sakamoto, Nagasaki,... 

Department of Molecular Medicinal Sciences, Graduate School of Biomedical Sciences, Nagasaki University, 1-14, Bunkyo-machl, Nagasaki 852-8521, Japan Fax (+81) 95 819 2476 e-mall onomura nagasakl-u.ac.jp... 

Department of Laboratory Medicine and tThe Unit of Generai Medicine Nagasaki University Schooi of Medicine Nagasaki, Japan... 

The structurally-related 7-lactams salinosporamide A 1, omuralide 2 and lactacystin 3, of bacterial origin, inhibit proteasome activity, and so are of interest as lead compounds for the development of anticancer agents. Barbara . M. Potts of Nereus Pharmaceuticals in San Diego has reported (J. Med. Chem. 2005,48,3684) a detailed structure-activity studies in this series, and E.J. Corey of Harvard University has prepared (J. Am. Chem. Soc. 2005,127, 8974, 15386) several interesting structural analogues. Susumi Hatakeyama of Nagasaki University, building on previous work in this area, has reported (J. Org. Chem. 2004, 69,7765) a synthesis of 2 and 3 from Tris. 

Department of Cariology, Nagasaki University Hospital, Nagasaki, Japan (107)... 

Department of Industrial Chemistry, Faculty of Engineering, Nagasaki University, Bunkyo-machi, Nagasaki, Japan 852. 

Nagasaki University Graduate School of Biomedical Science, Nagasaki 852-8523, Japan... 

Dr. N. Morita from School, Medicine of Fukuoka University, Dr. T. Sato from Faculty of Engineering, Nagasaki University, and Prof. J. Sunamoto from Faculty of Engineering, Kyoto University for their cooperation and helpful suggestions. 

Acknowledgement. The authors wish to express their deep thanks to Profs. N. Kasai and Y. Kai, Osaka University, Prof. S. Akiyama and Dr. K. Nakashima, Nagasaki University, Dr. I. Tanigawa, Mr. K. Sugihara, Mr. S. Umeda, Dr. K. Hirose, Dr. Y. Ishizaki, and the other coworkers for their valuable contributions to this research. They are also indebted to the Ministry of Education, Science and Culture of Japan for a support by Grant-in-Aid for Scientific Research and to the Material Analytical Center of ISIR, Osaka University for spectral measurements and microanalysis. 

Department of Chemistry, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852, Japan. 

AKIRA HOSOMI and YOSHINORITOMINAGA University of Tsukuba and Nagasaki University, Japan... 

Zenitani, B. Department of Fisheries, Nagasaki University, Sasebo, Japan (7, 41)... 

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