Events
Date 13 Jan 2025
Time 5:30 pm - 6:30 pm (HKT)
Venue Lecture Theatre P1, Chong Yuet Ming Chemistry Building
Speaker Prof. Alison Frontier
Institution University of Rochester
Self Photos / Files - Prof. Alison Frontier Seminar Poster
 
Title:
Iterative Cationic Cyclizations for the Synthesis of Polycyclic Targets
 
Schedule:
Date: 13th January, 2025 (Monday)
Time: 5:30 - 6:30 pm (HKT)
 
Venue: Lecture Theatre P1, Chong Yuet Ming Chemistry Building
 
Speaker:
Prof. Alison Frontier
University of Rochester
 
Abstract:
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.
 
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