Opening Access to New Chiral Macrocycles: From Allenes to Spiranes

Chiral macrocycles offer great potential and versatility regarding their applications. They have been employed in asymmetric catalysts, as chiral sensors, and as chiral supramolecular frameworks. For these reasons, they have been attracting increasing interest over the years. Despite all of the work developed in this area, most of the reported chiral macrocycles are not conformationally stable and present weak chiroptical responses. Such features substantially limit the scope of applications for these compounds. On the other hand, we have shown that axially chiral allenes can be introduced into macrocycles, conferring conformational stability and outstanding chiroptical responses. However, these allenes photoisomerize when conjugated with electron-donating groups, hampering the possibility of synthesizing systems with tuned optical properties. To overcome all of these limitations with a single structural motif, we propose the use of spiranes to construct new stable, conformationally rigid, and chemically ...