Aziridines, from allylic imines

Dai and coworkers have investigated the addition of ylides derived from allylic sulfonium salts to IV-sulfonyl imines derived from aromatic aldehydes to produce 2-vinyl aziridines [98]. The general reaction studied is shown in Eq. (69), where a sulfonium salt 285 can be converted to its ylide in situ under either phase transfer conditions, or by use of a strong amides base, and then combined with an N-sulfonyl imine to provide a 2-vinyl aziridine 286. In gene-... 

Reduction of iV-(3-bromopropyl) imines gives a bromo-amine in situ, which cyclizes to the aziridine. Five-membered ring amines (pyrrolidines) can be prepared from alkenyl amines via treatment with N-chlorosuccinimide (NCS) and then BusSnH. " Internal addition of amine to allylic acetates, catalyzed by Pd(PPh3)4, leads to cyclic products via a Sn2 reaction. Acyclic amines can be prepared by a closely related reaction using palladium catalysts. Three-membered cyclic amines (aziridines)... 

Based on results presented in Scheme 37, Logothetis suggested that the thermal decomposition products from the olefinic azides in the scheme are derived from triazoline intermediates formed by an intramolecular cycloaddition reaction and not by fragmentation of the azido group to a nitrene.100 However, allyl azide and 4-azido-l-pentene do not undergo internal cycloaddition because of the strain in the corresponding triazoline they fail to give aziridines and imines upon thermolysis.100... 

Other types of allylic amination reactions include a variety of indirect approaches such as reduction of a,P-unsaturated imines and oximes, rearrangement of aziridines, and elimination of water from vicinal amino alcohols. However, these reactions will not be considered in this chapter [2]. 

In a typical example for aziridine synthesis,, y-allyl tetrahydrothiophenium bromide 618 was smoothly deproto-nated with strong base to provide an ylide which adds to a variety of N-protected imines. For the iV-tosyl aldimine 619 derived from isovaleraldehyde, the corresponding vinyl aziridine 620 is formed in fair yield as a mixture of stereoisomers (Scheme 151) <2004TL1589>. 

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