Synthesis of (-)-Spirotryprostatin B

Significance

The salient feature of the Carreira synthesis of (-)-Spirotryprostatin B is a MgI₂-mediated ring-expansion reaction via putative intermediate D to construct the spiro[pyrrolidine-3,3′-oxindole] core. The Carreira group has also applied the MgI₂-mediated ring expansion to the synthesis of Horsifiline (C. Fischer, C. Meyers, E. M. Carreira Helv. Chim. Acta 2000, 83, 1175-1181) and Strychnofoline (A. Lerchner, E. M. Carreira J. Am. Chem. Soc. 2002, 124, 14826-14827).