Corrigendum: Exploitation of the Ugi 5-Center-4-Component Reaction (U-5C-4CR) for the Generation of Diverse Libraries of Polycyclic (Spiro)Compounds - Moni, Lisa; De Moliner, Fabio; Garbarino, Silvia; Saupe, Jörn; Mang, Christian; Basso, Andrea (Frontiers in Chemistry, 2018)