Fragment Coupling Approach to Diaporthein B

Area of Science:

• Organic Chemistry
• Natural Product Synthesis

Background:

• Pimarane diterpenes, found in plants, fungi, and bacteria, exhibit antimicrobial and antiproliferative properties.
• These compounds feature a characteristic tricyclic carbon scaffold with multiple quaternary centers.
• Diaporthein B is a notably highly oxidized member of this natural product family.

Purpose of the Study:

• To develop novel synthetic strategies for diaporthein B.
• To explore convergent, fragment-based approaches for complex diterpene synthesis.

Main Methods:

• Two distinct synthetic routes were designed and executed.
• Key reactions included diastereoselective fragment coupling, carbonylative Stille cross-coupling, tandem aldol cyclization-deprotection, diastereoselective 1,4-addition, and epoxidation-ring opening.

Main Results:

• The first strategy successfully constructed the tricyclic carbon scaffold of diaporthein B.
• The second strategy yielded a highly oxidized intermediate with two elaborated cyclohexane rings.
• Novel chemical transformations were employed, including a direct α-hydroxyketone synthesis from a vinyl iodide.

Conclusions:

• The developed synthetic methodologies provide valuable tools for accessing complex pimarane diterpenes.
• These strategies may facilitate future total synthesis of diaporthein B and related natural products.
• The novel chemistry expands the synthetic toolkit for natural product synthesis.