Satoru Masamune died on November 9, 2003 at the age of 75 from complications following a cardiac arrest. Born in Fukuoka (Japan), he completed his science degree in 1952 at Tohoku University under the guidance of Tetsuo Nozoe. He completed his PhD in 1957 at the University of California, Berkeley (USA), under the supervision of Henry Rapoport, as one of the first Fulbright Fellows. He went as a postdoctoral fellow to Eugene van Tamelen at the University of Wisconsin (1956 – 1959), and then took up positions first at the Mellon Institute (1960 – 1964), and then at the University of Alberta (1964 – 78), before moving to the Massachusetts Institute of Technology (MIT) in 1978, where he became the Arthur C. Cope Professor in 1991. Masamune received the Award for Creative Work in Synthetic Organic Chemistry of the American Chemical Society in 1978 and the A. C. Cope Scholar Award in 1987. He was a Fellow of the Royal Society of Canada, a Fellow of the American Academy of Arts and Sciences, and a Centenary Scholar of the Chemical Society in London (1980), and he received the Fujiwara Award in 1997. He retired in 2000 but continued to visit his MIT office nearly every day until his death. The breadth of Masamune<s interests and accomplishments is extraordinary. His selection of research projects was always guided by what he identified as the most important problems of the day, even if that might require him to abandon his current comfortable and familiar sphere of research in which he had perhaps already established his preeminence. He made significant contributions to two broad fields, the synthesis of natural products and the chemistry of small ring systems. Masamune<s research interests spanned topics ranging from the synthesis of organic and organometallic compounds to the chemistry of theoretically interesting molecules, and later included catalytic antibodies, enzyme-catalyzed reactions, and polymer gels. When he visited Columbia University in the late 1970s, his interests overlapped with those of Ron Breslow, Tom Katz, Gilbert Stork, and Nick Turro; Koji Nakanishi was the only one whose research interests did not overlap with those of Masamune. Masamune is best known for his work on methods for the synthesis of naturally occurring substances, particularly compounds with biological activity. He attracted the attention of the chemical community early in his career when he published three consecutive singleauthor communications in JACS in 1964 on the synthesis of the complex polycyclic diterpene alkaloids kaurene, garryine, and atisine. [1] He reported these results as an invited speaker at the 3rd IUPAC Symposium onNatural Products Chemistry in Kyoto in 1964, which was attended by 1500 scientists. This probably triggered his invitation by Ray Lemieux to join the faculty of the University of Alberta. Masamune pioneered the development of a general strategy known as “double asymmetric synthesis”,[2] which in the 1980s and 1990s revolutionized the ability of chemists to prepare certain classes of molecules with complex threedimensional structures. He and his students demonstrated the power of this strategy in syntheses of a number of organic compounds with high structural complexity. Particularly significant were his landmark syntheses of several important macrolide antibiotics and carbohydrates, including the l-hexoses as mirror-image isomers of the naturally occuring sugars.[3] His contributions to chemistry also include the first syntheses of a number of unusual and theoretically important nonnatural compounds, whose high degree of strain and instability had defeated previous synthetic efforts. Especially significant was his work on the synthesis of cyclobutadiene,[4] [10]-annulenes, and small ring compounds of Si, Ge, and Sn. Masamune was a constant source of off-beat humor, which came from his uniquely honest and candid nature. On the other hand, he often could not comprehend common humor, reflecting his purist personality. According to his wife Takako he was not known for, or was incapable of helping with chores around the house. However, he was a truly warm, loving, devoted husband, and an emotional pillar. He was extremely bright, always did his best, and had an unusually unspoiled personality. He had a great passion for classical music, especially for Beethoven, and had been an excellent pianist since his youth. He regularly attended concerts of the Boston Symphony Orchestra and was a close friend of the conductor Seiji Ozawa. He also avidly followed baseball and sumo wrestling. We will all miss this smiling person, who was always willing to help. He is survived by his wife and two children.