Total Synthesis of Loroxanthin.

Area of Science:

• Organic Chemistry
• Natural Product Synthesis
• Carotenoid Chemistry

Background:

• Loroxanthin is a naturally occurring xanthophyll carotenoid.
• The total synthesis of complex natural products presents significant chemical challenges.
• Efficient synthetic routes are crucial for studying and potentially utilizing such molecules.

Purpose of the Study:

• To achieve the first total synthesis of loroxanthin.
• To develop a robust and efficient synthetic strategy for loroxanthin.
• To establish a reliable method for obtaining pure loroxanthin for further research.

Main Methods:

• The synthesis employed a Horner-Wadsworth-Emmons reaction as the key C-C bond-forming step.
• Preparation of the C25-apocarotenal intermediate involved a Stille coupling reaction.
• The C15-phosphonate fragment was synthesized from a chiral precursor obtained via chiral HPLC resolution.

Main Results:

• The total synthesis of loroxanthin (1) was successfully accomplished.
• Key intermediates, C25-apocarotenal (8) and C15-phosphonate (25), were synthesized and coupled.
• The synthesis utilized silyl-protected hydroxyl groups for strategic protection and deprotection.

Conclusions:

• The study reports the first total synthesis of loroxanthin.
• The developed synthetic route provides access to loroxanthin and potentially its analogs.
• This work lays the foundation for further investigations into the chemistry and biology of loroxanthin.