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Updated: Jan 21, 2026

Free Radicals in Chemical Biology: from Chemical Behavior to Biomarker Development

Free Radicals in Chemical Biology: from Chemical Behavior to Biomarker Development

Published on: April 15, 2013

A Radical-Polar Crossover Annulation To Access Terpenoid Motifs.

William P Thomas¹, Devon J Schatz¹, David T George¹

¹Department of Chemistry , University of California, Irvine , Irvine , California 92697-2025 , United States.

Journal of the American Chemical Society

|July 23, 2019

Summary

A novel catalytic annulation reaction enables efficient synthesis of complex terpenoid structures. This method provides a direct route to molecules like forskolin under mild conditions.

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Area of Science:

Organic Chemistry
Catalysis
Synthetic Methodology

Background:

Terpenoids are a diverse class of natural products with significant biological activities.
Efficient synthetic routes to complex terpenoid scaffolds are highly sought after in medicinal chemistry.
Existing methods for terpenoid synthesis can be lengthy and require harsh conditions.

Purpose of the Study:

To develop a new catalytic radical-polar crossover annulation reaction.
To provide a direct and mild method for accessing complex terpenoid motifs.
To demonstrate the utility of this new chemistry in the total synthesis of a valuable natural product.

Main Methods:

Catalytic radical-polar crossover annulation of unsaturated carbonyl compounds.
Optimization of reaction conditions for mildness and efficiency.
Application of the developed annulation in a multi-step synthesis.

Main Results:

A new annulation strategy was established using catalytic radical-polar crossover.
The reaction proceeds under exceptionally mild conditions.
The chemistry provides direct access to complex terpenoid structures.
Successful synthesis of forskolin in 14 steps from commercial starting materials was achieved.

Conclusions:

The developed catalytic annulation is a powerful tool for constructing complex terpenoid frameworks.
This methodology offers a mild and efficient alternative to existing synthetic routes.
The synthesis of forskolin highlights the practical applicability of this novel chemistry.