A Stereoselective Oxidative Dimerization En Route to (-)-Lomaiviticin A

Area of Science:

• Organic Chemistry
• Natural Product Synthesis

Background:

• (-)-Lomaiviticin A is a potent cytotoxic bacterial metabolite with a unique C2-symmetric structure.
• The synthesis of complex natural products like (-)-lomaiviticin A presents significant challenges in stereocontrol and efficiency.

Purpose of the Study:

• To develop a stereoselective synthesis of a dimeric diazofluorene precursor (15) for (-)-lomaiviticin A (1).
• To establish an efficient route from a tetracyclic diol (5) to a diketone (4).

Main Methods:

• A five-step conversion of tetracyclic diol 5 to diketone 4 with 30% overall yield.
• Oxidative dimerization of enoxysilane 14 to yield dimeric diazofluorene 15.
• Deprotection and 2D NMR analysis for stereochemical determination.

Main Results:

• The synthesis achieved a 56% yield of the dimeric diazofluorene 15.
• The dimerization proceeded with high diastereoselectivity (15:1:0).
• The major diastereomer was confirmed to have the (2S,2'S) configuration, matching that of (-)-lomaiviticin A.

Conclusions:

• A stereoselective synthesis of a key precursor for (-)-lomaiviticin A has been established.
• The developed methodology provides a viable strategy for the synthesis of this complex natural product.