5th "Prof. G. K. Trivedi Annual Award Lecture" by Prof. Viresh H. Rawal (University of Chicago)

17 Aug 2026
P.C. Saxena auditorium

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Speaker: Prof. Viresh H. Rawal
Department of Chemistry
University of Chicago
Chicago, IL 60637 USA

Title: "Unified Strategy for the Synthesis of Veratrum
Alkaloids: Convergent Assembly and Late-Stage
Skeletal Reorganization."

Date: Monday, August 17, 2026

Time: 17:00 hrs

Venue: P. C. Saxena Auditorium, IIT Bombay

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Talk Title : "Unified Strategy for the Synthesis of Veratrum Alkaloids: Convergent Assembly and Late-Stage Skeletal Reorganization."
Abstract
The synthesis of complex natural products is most rewarding when it transcends the preparation of a single target and instead provides a strategic framework for accessing an entire family of structurally related molecules. Such an approach requires identifying simplifying transformations that rapidly build molecular complexity while also enabling divergence to distinct structural types. It is with this objective that we undertook the synthesis of alkaloids belonging to the Veratrum family, whose intricate C-nor-D-homo steroid skeletons and diverse ring connectivities have challenged synthetic chemists for decades. In this presentation, I will discuss the strategic and tactical considerations that guided our development of a unified, de novo approach to these remarkable natural products. Central to this work is a convergent strategy featuring a transition-metal-catalyzed [2 + 2 + 2] cycloisomerization that assembles three rings of the cevanine framework in a single operation. I will first describe the synthesis of (+)-heilonine, which established this general strategy and provided a versatile platform for subsequent investigations. I will then discuss our efforts toward (–)-verarine, in which selective late-stage bond ablation of the cevanine skeleton enabled efficient access to the veratramine subclass of alkaloids. Finally, I will describe the synthesis of (+)-ussuriedine, where a late-stage Stevens rearrangement forged the defining carbon–carbon bond of its unprecedented azatricyclic framework while simultaneously providing a plausible hypothesis for its biosynthesis. Collectively, these studies illustrate how the pursuit of complex molecule synthesis can inspire unconventional strategic disconnections, and provide insights into natural product biosynthesis.
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