Cyclic stannylenes, synthesis

Danishefsky, S J, Hungate, R, Schulte, G, Total synthesis of octosyl acid. A. Intramolecular Williamson reaction via a cyclic stannylene derivative, J. Am. Chem. Soc., 110, 7434-7440, 1988. 

Scheme 3. Synthesis of cyclic diaminosilylenes, -germylenes and stannylenes.

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