Chemistry and Materials Science Seminar: Iterative Cationic Cyclizations for the Synthesis of Polycyclic Targets

Chemistry and Materials Science Seminar
Iterative Cationic Cyclizations for the Synthesis of Polycyclic Targets

Dr. Alison Frontier
Professor of Chemistry
University of Rochester

Event Details:
The development of new iterative cyclization strategies for rapid assembly of complex molecules will be described. These strategies have arisen from our work on the Nazarov pentannulation; an electrocyclic, cationic cyclization that occurs diastereospecifically. The reaction cascades combine halo-alkynyl Prins chemistry and halo-Nazarov cyclization chemistry, through a series of cationic intermediates. The cationic cascades resemble classical polyene cyclization, but follow irregular patterns to deliver a variety of densely functionalized scaffolds in one or two steps. A range of fused and spirocyclic ring systems can be accessed, containing functionalized cyclopentanes, oxygen and nitrogen heterocycles, and a vinyl halide synthetic handle. The sequences are stereocontrolled, and can produce enantiopure adducts.
Strategically, the method couples two simple precursors: an enyne/ arenyne and the carbonyl derivative that serves as the initiating carbon. The initiating carbon (in blue) can be an aldehyde, ketone, imine, N,O-acetal, acetal, ketal or enol ether, and subsequent iterative cyclization converts the initiating carbon into an sp3 center (blue) within a polycyclic framework.

Bio:
Dr. Alison J. Frontier was born and raised in suburban Detroit, Michigan. She attended Harvard University, where she worked in the laboratory of Professor Yoshito Kishi. In June 1992 she graduated with an AB in chemistry and became a research scientist at Merck Research Laboratories in Rahway, New Jersey, in the Basic Medicinal Chemistry division. She enrolled in the doctoral program at Columbia University in September 1994, conducted graduate work under the direction of Professor Samuel Danishefsky, and received her Ph.D. in June 1999. She was an NIH postdoctoral fellow in the laboratory of Professor Barry Trost at Stanford University from 1999-2001, and began her independent career at the University of Rochester in January 2002. Dr. Frontier was promoted to associate professor in 2008 and professor in 2013. In 2004, she launched "not voodoo" a website dedicated to students who are beginning independent experimentation.

Intended Audience:
All are Welcome!

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