Three Different Types of Asymmetric Polymerization of Aryl Isocyanides by Using Simple Rare-Earth Metal Trialkyl Precursors

Three different types of asymmetric polymerization of aryl isocyanides containing helix-sense-selective polymerization of achiral aryl isocyanides with d/l-lactide as the chiral additive, asymmetric induced polymerization of chiral aryl isocyanides, and helix-sense-selective copolymerization of chiral and achiral aryl isocyanides with chiral amplification have successfully been implemented by using two kinds of achiral monocation [LnR₂(THF)_n]⁺ or dication species [LnR­(THF)_n]²⁺ in situ generated from two series of simple rare-earth metal trialkyl precursors (LnR₃(THF)_n, Ln = Sc, Lu, Y; R = −CH₂SiMe₃, -o-CH₂C₆H₄NMe₂; n = 0, 2). As a result, various optically active poly­(aryl isocyanide)­s having one-handed helical conformations and/or aggregation-induced emission (AIE) nature are prepared. A possible coordination mechanism is also proposed. Such a catalytic system affords a new design concept of simple, efficient, and superior rare-earth metal catalysts for asymmetric polymerization of functional isocyanides.