New Synthetic Methodologies to Access N-Heterocycles

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The proposed research falls in the category of synthetic organic chemistry, more specifically developing new reactions and methods of synthesis for application in natural products synthesis. We also propose to synthesize a new thermo- and photoresponsive scaffold to make molecular switches.The proposed research is divided in four parts, the first is concerned with developing a new (4+1)-cycloaddition reaction of chromium aminocarbenes (CAMCs) destined to make 5-membered N-heterocycles. The latter are molecular fragments ubiquitously found in natural alkaloids. The second part is a new twist to the Nobel-Prize winning ring-closing metathesis (RCM) reaction: we have found and would like to exploit a newly discovered reaction of CAMCs to make dienamines. Such fragments can be very useful to make more complex N-heterocyclic structures. The third part is concerned with the photochemical or thermal ring-contraction of N-activated lactams. It is also aimed at making N-heterocycles and ultimately natural alkaloids. We propose to study, develop, and expand each methodology. Mechanistic aspects of the reactions will be probed to better understand them and thus be better able to control reactivity and selectivity issues. We also propose to use each method in total synthesis of natural alkaloids as a way to underscore their usefulness.The last part of the proposed research is a venture into a new area of research in our laboratory. We believe we have discovered a new structural scaffold that could be used to make molecular switches. The scaffold is easily prepared and one such molecular scaffold, previously prepared for a totally different purpose, displayed the main attributes of a molecular switch: it isomerizes thermally and photochemically between two stable states. However, it needs to be studied and developed before we can call it a new thermo- and photoresponsive core structure. The synthesis is modular allowing for easy structural changes. We propose, at this stage, a proof of concept and will leave more complex studies and devices for a next discovery grant application.