Toward the macrocidins: macrocyclization via Williamson etherification of a phenolate.

Area of Science:

• Organic Chemistry
• Natural Product Synthesis
• Agrochemical Research

Background:

• Macrocyclic 3-acyltetramic acids are vital precursors for macrocidin A, a potent fungal herbicide.
• Efficient synthesis of these macrocycles is crucial for developing new agrochemicals.
• Previous synthetic routes faced challenges in macrocycle closure.

Purpose of the Study:

• To develop an efficient synthetic route for macrocyclic 3-acyltetramic acids.
• To establish a novel method for macrocycle ring closure.
• To provide accessible precursors for the fungal herbicide macrocidin A.

Main Methods:

• Synthesis of macrocyclic 3-acyltetramic acid precursors.
• In situ generation of an omega-bromo phenolate intermediate.
• Palladium-catalyzed O-deallylation for in situ intermediate generation.
• Williamson etherification for crucial macrocycle closure.

Main Results:

• The synthesis of macrocyclic 3-acyltetramic acids was successfully achieved.
• Macrocycle closure was accomplished in excellent yield using a novel Williamson etherification.
• The key intermediate was generated efficiently via palladium-mediated O-deallylation.

Conclusions:

• A novel and efficient method for synthesizing macrocyclic 3-acyltetramic acids has been developed.
• The reported strategy provides a robust route to macrocidin A precursors.
• This work advances the synthesis of important agrochemical compounds.