Enantiomerization Dynamics and a Catalytic Dynamic Resolution of N-Trimethylallyl-2-lithiopyrrolidine

摘要

Lithium alkyls are ubiquitous in organic synthesis. In one popular application, stoichiometric chiral ligands such as (-)-sparteine 1, when complexed to sec-butyllithium, form a chiral base that is capable of enantioselective deprotonation. Recently, O'Brien has shown that substoichiometric amounts of 1, in combination with bispidine 2, are also capable of asymmetric deprotonation. The enantioselective deprotonation of N-Boc-pyrrolidine is conducted at -78 ℃, and at this temperature, N-Boc-2-lithiopyrrolidine is configurationally stable when coordinated to either 1 or 2, consistent with a kinetically controlled enantioselective deprotonation.