Synthesis, properties, and two-dimensional adsorption characteristics of 5-aminohexahelicene
Van der Meijden, M., Gelens, E., Murillo-Quirós, N., Fuhr, J., Gayone, E., Ascolani, H., Wurst, K., Lingenfelder, M., & Kellogg, R. (2016). Synthesis, properties, and two-dimensional adsorption characteristics of 5-aminohexahelicene. Chemistry - A European Journal, 22(4), 1484-1492.
A convergent synthesis of racemic 5-aminohexahelicene is described. Cross-coupling reactions are used to assemble a pentacyclic framework, and a metal-catalyzed ring-closure comprises the final step. The enantiomers were separated by means of chromatography and the absolute configurations were assigned by comparison of the CD spectra with hexahelicene. The t1/2 value for racemization at 210 8C was approximately 1 hour. Scanning tunneling microscopy (STM) measurements were carried out on enantiopure and racemic samples of aminohelicene on Au(111) under ultrahigh vacuum (UHV) conditions.