Highly modular assembly of cationic helical scaffolds: rapid synthesis of diverse helquats via differential quaternization

<p>A protocol for rapid and highly modular assembly of a diverse set of helquats is described. From a common bis-isoquinoline precursor, two successive distinct pyridine-type nitrogen quaternizations followed by rhodium-catalyzed 2+2+2 cycloaddition afford non-symmetric 7helquats. This route allows for straightforward molecular editing of cationic helical skeletons as exemplified by the synthesis of 15 different 5-, 6-, and 7helquats. © 2010 Elsevier Ltd. All rights reserved.</p>