C2-symmetric chiral pentacyclic

Nagasawa and co-workers developed the C2-symmetric chiral pentacyclic guanidine 11 as a chiral phase-transfer catalyst for the enantioselective alkylation of tert-butyl glycinate Schiff base (Equation 10.25) [53]. 

The Shi epoxidation was the key step in E.J. Corey s total synthesis of the chiral C2-symmetric pentacyclic... 

Xiong ZM, Corey EJ (2000) Simple Enantioselective Total Synthesis of Glabrescol, a Chiral C2-Symmetric Pentacyclic Oxasqualenoid. J Am Chem Soc 122 9328... 

Xiong and Corey also used Rieke barium in an enantioselective total synthesis of glabrescol, a chiral C2-symmetric pentacyclic oxasqualenoid. The first step is shown in Scheme 10.4 [5]. 

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