Polymerization of Substituted Acetylenes Using Well‐Defined Rhodium Complex Catalyst. Chirality Transfer and Amplification in Chiral‐Chiral Block and Random Copolymers

Block and random copolymers are synthesized by the copolymerization of N‐tert‐butoxycarbonyl‐?‐valine 4‐ethynylanilide ( 1L ) and N‐tert‐butoxycarbonyl‐d‐valine 4‐ethynylanilide ( 1D ) using (nbd)Rh{C(Ph) = CPh₂}(PPh₃)]/PPh₃ as a catalyst. The size exclusion chromatography (SEC) peaks show narrow polydispersities from the first stage polymerization to the second one in the block copolymerization. Poly( 1L ₂₅‐ran‐ 1D ₂₅) exhibits no circular dichroism (CD) signal, while poly( 1L ₂₅)‐block‐poly( 1D ₂₅) exhibits weak CD signals with the same sign as those of poly( 1L ₅₀), suggesting the occurrence of chirality transfer from the poly( 1L ) block to poly( 1D) block. The relationship between the |g| values and 1L / 1D contents of the block copolymers becomes almost linear at the region of each unit larger than 60%. On the other hand, the relationship between these two factors of the random copolymers is convex upward.