5,10-diaza helicenes

The diaza[7]helicene 136 (Pig. 51) has been separated completely into the enantiomers using M-(—)-BPA The successful separations of heterohelicenes are com-... 

Control of reactivity by activating a strong stereoelectronic effect The differences in the donor ability of heteroatoms can be used in a variety of ways. For example, it leads to a convenient synthesis of diaza[4] helicenes from tris(2,6-dimethoxyphenyl)methyl cation and primary amines (Figure 10.21). Again, the transformation is driven by favorable thermodynamics originating from a delocalizing donor-acceptor interaction between nitrogen lone pairs and benzylic cations. 

Figure 10.21 Synthesis of diaza[4]helicenes driven by thermodynamics of cation stabilization.

Wallabregue, A., Sherin, P, Guin, J., Besnard, C., Vauthey, E., Lacour, Jdr6me. (2014). Modular Synthesis of pH-Sensitive Fluorescent Diaza[4]helicenes. European Journal of Organic Chemistry, 6431-6438. 

Scheme 2.9 Application of a Buchwald-Hartwig reaction for the synthesis of functionalized 5,10-diaza[5]helicenes by Dehaen and coworkers [40]. (Note the structures are helicoidal.)...

Misek, J., Teply, F., Stara, I.G., et al. (2008) A straightforward route to helically chiral N-heteroaromatic compounds practical synthesis of racemic 1,14-diaza[5]helicene and optically pure 1- and 2-aza [6]helicenes. Angewandte Chemie International Edition, 47(17), 3188-3191. 

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