1269473-20-2Relevant articles and documents
Late-stage diversification of chiral N-heterocyclic-carbene precatalysts for enantioselective homoenolate additions
Zheng, Pinguan,Gondo, Chenaimwoyo A.,Bode, Jeffrey W.
, p. 614 - 620 (2011/10/12)
A library of chiral triazolium salts has been prepared by late-state diversification of a triazolium amine salt. By utilizing a primary amine as a functional handle, a single triazolium salt can be transformed into a variety of chiral N-heterocyclic carbene precatalysts. This approach makes the preparation of chiral N-heterocyclic carbenes possible by a single-step modification of a triazolium salt, rather than the usual need for multistep organic synthesis and challenging heterocycle formation for each member of a catalyst library. We have screened these catalysts for control of diastereo- and enantioselectivity in a γ-lactam-forming reaction between α,β-unsaturated aldehydes and cyclic ketimines. Saving the best for last: Enantioselective homoenolate additions have been hindered by the challenge of synthesizing N-mesityl-substituted azolium salts. A library of pyrrole-functionalized chiral triazolium salts was prepared by direct modification of the preformed azolium core. Copyright
