Norrisolide: total synthesis and related studies

Area of Science:

• Organic Chemistry
• Natural Product Synthesis
• Marine Natural Products

Background:

• Norrisolide is a marine spongiane diterpenoid.
• Its structure features a unique fused gamma-lactone-gamma-lactol ring system and a bicyclic core.
• Diterpenes are complex natural products with diverse biological activities.

Purpose of the Study:

• To develop a stereoselective synthesis of the natural product (+)-norrisolide.
• To establish an efficient method for constructing the characteristic gamma-lactone-gamma-lactol motif.
• To explore novel synthetic strategies for complex marine diterpenes.

Main Methods:

• Developed a synthesis based on ring expansion of a fused cyclopropyl ester to create the lactone-lactol system.
• Employed a sterically demanding coupling reaction to form the C9-C10 bond, linking the bicyclic systems.
• Utilized a late-stage Baeyer-Villiger oxidation to install the C19 oxygen atom.

Main Results:

• Achieved a stereoselective synthesis of (+)-norrisolide.
• Demonstrated an expedient route to the fused gamma-lactone-gamma-lactol core structure.
• Successfully coupled the two key bicyclic fragments and performed late-stage functionalization.

Conclusions:

• The presented synthetic strategy provides an efficient pathway to (+)-norrisolide and related marine diterpenes.
• The ring expansion of cyclopropyl esters offers a valuable method for constructing gamma-lactone-gamma-lactol motifs.
• This work contributes to the synthetic accessibility of complex natural products from marine sources.