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.