Dartmouth Events

Bio: Christopher “Kit” Colin Cummins benefited from formative undergraduate research experiences carried out sequentially in the laboratories of Professors Susan E. Kegley, James P. Collman, and Peter T. Wolczanski, respectively of Middlebury College, Stanford University and Cornell University. He graduated from the latter institution with an A.B. degree in 1989. Following this he undertook inorganic chemistry graduate studies under the direction of Professor Richard R. Schrock at the Massachusetts Institute of Technology, from which he obtained his Ph.D. degree in 1993 with a thesis entitled “Synthetic Investigations Featuring Amidometallic Complexes”. Also in 1993 Kit joined the chemistry faculty at MIT as an Assistant Professor; in 1996 he was promoted to the rank of Professor, and in 2015 he was named the Henry Dreyfus Professor of Chemistry.

Abstract: Three-membered ring compounds are valuable building blocks in synthetic chemistry. Epoxides, aziridines, and cyclopropanes are available from alkenes via transition-metal catalyzed oxygen atom, nitrene group, or carbene transfer reactions. Each of these iconic alkene functionalization reactions requires a source of the oxygen, nitrene, or carbene, such as respectively iodosylbenzene, organic azides, or diazoalkanes. To date, the lack of a similar reaction for phosphinidene transfer to alkenes to afford the corresponding three-membered ring PC₂ compounds, phosphiranes, can be ascribed to the absence of a suitable phosphinidene source. In the present work we show that RPA (A = C₁₄H₁₀ or anthracene) compounds are suitable phosphinidene sources for a reaction that can be catalyzed by the simple Fp₂ dimer, where Fp = CpFe(CO)₂. The Fp-catalyzed reaction is successful for
styrenic olefins, or ones possessing electron-withdrawing substituents. Another catalytic reaction has been discovered that leverages the highly strained phosphatetrahedrane P(C^tBu)₃ as the phosphinidene source. The latter reaction, which is nickel-catalyzed, proceeds at room temperature and is successful for unactivated alkenes, including ethylene. Time permitting, the synthesis and reactivity of a PN synthon, azidophosphine N₃PA, will be discussed.

Join Zoom Meeting: https://mit.zoom.us/j/95629434085?pwd=Q2NXNjdmdFRZWGpPck9MSHJCL1RYQT09
ID: 956 2943 4085
Passcode: 197434