Cobalt versus Osmium: Control of Both trans and cis Selectivity in Construction of the EFG Rings of Pectenotoxin 4

• Published in: Angewandte Chemie International Edition Vol. 56; no. 47; pp. 14883 - 14887
• Main Authors: Roushanbakhti, Ahria, Liu, Yifan, Winship, Paul C. M., Tucker, Michael J., Akhtar, Wasim M., Walter, Daryl S., Wrigley, Gail, Donohoe, Timothy J.
• Format: Journal Article
• Language: English
• Published: Germany 20.11.2017
• Subjects: cobalt; osmium; oxidation; pectenotoxin; transition-metal catalysis; oxidation; osmium; transition-metal catalysis; pectenotoxin; cobalt
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201708278

Catalytic oxidative cyclisation reactions have been employed for the synthesis of the E and F rings of the complex natural product target pectenotoxin 4. The choice of metal catalyst (cobalt‐ or osmium‐based) allowed for the formation of THF rings with either trans or cis stereoselectivity. Fragment union using a modified Julia reaction then enabled the synthesis of an advanced synthetic intermediate containing the EF and G rings of the target. Two types of oxidative cyclisation reaction, utilising either osmium or cobalt catalysis, provide complete control of the relative stereochemistry of THF rings embedded in the complex pectenotoxin‐4 ring system. In this manner, rapid access to either trans (Co) or cis (Os) 2,5‐disubstituted THF rings of the natural product molecule was facilitated.