Asymmetric Total\nSyntheses of Sarglamides A, C, and\nE

The asymmetric total syntheses of sarglamides A, C, and\nE in concise\nand protecting group free fashion is disclosed. Key steps involve\nan <i>endo</i>-selective Diels–Alder reaction to\nconstruct the bicyclo[2.2.2]nonane framework, a nucleophilic addition\nand an intramolecular <i>aza</i>-Michael addition to install\nthe pyrrolidine ring, and a final cinnamoylation reaction. Sarglamide\nC is biomimetically transformed into E through a Brønsted acid\nmediated oxy-cyclization. Sarglamide D is also accessible from C based\non Yue’s research. This work provides an efficient asymmetric\napproach to the syntheses of sarglamides and also provides insights\ninto understand the plausible biogenetic pathway of these monoterpenoid–indolidinoid\nhybrid structures.