Aziridines from imines

Of course, the key limitation of the ylide-mediated methods discussed so far is the use of stoichiometric amounts of the chiral reagent. Building on their success with catalytic asymmetric ylide-mediated epoxidation (see Section 1.2.1.2), Aggarwal and co-workers have reported an aza version that provides a highly efficient catalytic asymmetric synthesis of trans-aziridines from imines and diazo compounds or the corresponding tosylhydrazone salts (Scheme 1.43) [68-70]. 

Diazoacetates are commonly used for the formation of aziridines from imines under Lewis or Bronsted acidic conditions - a process known as the aza-Darzens reaction. A useful twist on the reaction is achieved if the 1,2-addition intermediate undergoes deprotonation of the a proton prior to intramolecular aziridine formation with N2 extrusion. Such an interrupted aza-Darzens reaction accomplishes a... 

Diels-Alder additions in water. It also catalyzes aldehyde olefination with N2C(C02Et)2 and PPhs as oxygen sink. Its catalyzed decomposition of N2C(C02Et)2 leads to carbene transfer reactions allowing for the formation of epoxides from aldehydes and ketones, aziridines from imines and cyclopropanation. 

The Formation of Aziridines from Imines (1 + 2)AC,CC-cycto-Methylene-addition... 

Salto, T., Sakairi, M., Akiba, D. Enantioselective synthesis of aziridines from imines and alkyl halides using a camphor-derived chiral sulfide mediator via the imino Corey-Chaykovsky reaction. Tetrahedron Lett. 2001,42, 5451-5454. 

The synthesis of aziridines from imines and sulfur ylides has been reviewed in previous editions of PHC and is a well-known reaction. A current study reveals that telluronium ylides add to a,p-unsaturated imines through a Michael addition-elimination to the olefin followed by a second equivalent of telluronium ylide addition to the imine, which subsequently eliminates to form aziridines 137 and 138 in a ratio of 13 1 <05JA12222>. 

The sulfoniutn ylide-mediated epoxidation procedure developed by Aggarwal (see Section 4.8) has been adapted to the enantioselective synthesis of aziridines from imines bearing electron withdrawing groups on nitrogen. The... 

This review summarizes the best asymmetric methods for preparing epoxides and aziridines from aldehydes (or ketones) and imines. 

Asymmetric Synthesis of Epoxides and Aziridines from Aldehydes and Imines... 

AZIRIDINES FROM g-IODOCARBA-MATES 1,2,3,4-TETRAHYDRO NAPHTHALENE (1,2) IMINE, 51, 53... 

Diazoesters 22 have an electronically unique a-carbon atom. (Scheme 9) They are commonly used for the formation of aziridines 23 from imines 24. The intermediate (25) resulting from the addition of a-diazoesters 22 to the latter (24) can undergo elimination of the proton at the a-position prior to extrusion of molecular nitrogen. This interrupted aza-Darzens reaction allows for the direct alkylation of diazoesters 22 via cleavage of a carbon-hydrogen bond. 

---