Synthesis of ergostane-type brassinosteroids with modifications in ring A

Area of Science:

• Organic Chemistry
• Plant Biochemistry
• Synthetic Methodology

Background:

• Brassinosteroids are crucial plant hormones regulating growth and development.
• Synthesizing brassinosteroid metabolites is essential for understanding their biological functions.
• Existing methods for synthesizing brassinosteroid precursors are limited.

Purpose of the Study:

• To develop a versatile synthetic strategy for brassinosteroid biosynthetic precursors and metabolites.
• To utilize readily available phytohormones with a 2α,3α-diol moiety as starting materials.
• To efficiently introduce diverse functionalities onto the A ring of brassinosteroids.

Main Methods:

• Utilized epibrassinolide and epicastasterone (bearing a 2α,3α-diol) as starting materials.
• Employed a series of chemical transformations including Corey-Winter reaction, epoxidation, oxidation, and hydride reduction.
• Synthesized various A ring functionalities such as epoxides, diols, ketones, and hydroxyl groups.

Main Results:

• Successfully prepared a broad range of brassinosteroid biosynthetic precursors and metabolites.
• Demonstrated the efficiency of the developed protocol in generating diverse A ring modifications.
• Achieved synthesis of functionalities including Δ2, 2α,3α-epoxy, 2β,3β-epoxy, 2α,3β-dihydroxy, 2β,3α-dihydroxy, 2β,3β-dihydroxy, 3-keto, 3α-hydroxy, 3β-hydroxy, and 2α-hydroxy-3-keto derivatives.

Conclusions:

• The presented strategy offers a facile and efficient route to diverse brassinosteroid metabolites.
• This method expands the toolkit for synthesizing and studying brassinosteroid analogs.
• The protocol is valuable for further research into brassinosteroid biosynthesis and function.