Concise Total Synthesis of Tronocarpine

Area of Science:

• Organic Chemistry
• Synthetic Chemistry
• Natural Product Synthesis

Background:

• Chippiine-type indole alkaloids, including tronocarpine, possess complex pentacyclic structures.
• Efficient synthetic routes to these alkaloids are crucial for further biological investigation and drug discovery.

Purpose of the Study:

• To develop a concise total synthesis of tronocarpine.
• To establish a novel one-pot strategy for constructing the azabicyclo[3.3.1]nonane core found in chippiine-type alkaloids.

Main Methods:

• A one-pot tandem cyclization strategy was employed, starting from a functionalized indole derivative.
• The key cyclization sequence involved α,β-unsaturated aldehyde formation, intramolecular aldol reaction, lactamizations, and azide reduction.

Main Results:

• The total synthesis of tronocarpine was successfully accomplished in a concise manner.
• The one-pot tandem cyclization efficiently formed the pentacyclic skeleton with the characteristic azabicyclo[3.3.1]nonane core.
• Stereochemical control was achieved via the C14 stereocenter during the cyclization.

Conclusions:

• The developed synthetic strategy provides an efficient route to tronocarpine.
• This approach is adaptable for the synthesis of other chippiine-type alkaloids featuring the azabicyclo[3.3.1]nonane skeleton.
• The one-pot tandem cyclization represents a significant advancement in the synthesis of complex indole alkaloids.