Abstract
This Account describes the discovery and development of the catalytic
asymmetric aziridination reaction (AZ reaction) that has been the
subject of efforts in our laboratory over the last 12 years. The
optimized catalyst system involves catalysts generated from either
the VAPOL or VANOL ligand and triphenyl borate. These catalysts
are effective for formation of aziridines from the reaction
of imines that bear a N -benzhydryl substituent
with stabilized diazo compounds including the commercially available
ethyl diazoacetate (EDA). The reaction is general for N -benzhydryl imines prepared
from electron-rich and electron-poor aromatic aldehydes, as well
as from primary, secondary and tertiary aliphatic aldehydes. This
reaction is highly enantioselective and diastereoselective
giving cis -3-substituted aziridine-2-carboxylates
in excellent yields. This Account presents the scope of the AZ reaction
as defined by the work that has been done in our laboratory up to
the present time, as well as applications of the resulting aziridines
that have been demonstrated to date.
1 Introduction
2 Asymmetric Aziridination of Ethyl Diazoacetate with Imines
2.1 Discovery of the Original Catalytic System
2.2 Optimized Catalytic Asymmetric Aziridination System
2.3 Deprotection and Activation of Aziridine-2-carboxylates
3 Applications of Catalytic Asymmetric Aziridination
3.1 Ring Expansion of Aziridines to Oxazolidinones
3.2 Asymmetric Aziridination with Diazomethyl Vinyl Ketones
3.3 Diastereoselective Alkylation of cis -Aziridine-2-carboxylates
3.4 Synthetic Applications of the Catalytic Asymmetric Aziridination
Reaction
4 Conclusion and Outlook
Key words
aziridination - Lewis acids - chiral ligands - asymmetric catalysis
