Fig. 2: Quantitative synthesis of the hindered urea macrocycle HUM1.
From: Near quantitative synthesis of urea macrocycles enabled by bulky N-substituent
a Structures of N1, A1, their corresponding oligomer P1 and the dimeric macrocycle HUM1. b 1H NMR of the 1:1 mixture of N1 and A1 (50 mM) upon mixing and after 2 h incubation at 60 °C in CDCl3. The sharp and clean peaks demonstrated near quantitative yield of HUM1. c Single-crystal structure of HUM1. Color code: gray, C; white, H; blue, N; red, O. d Normalized GPC trace showing the formation process of HUM1 (200 mM in chloroform, 20 °C). After incubation, broad and multimodal peaks (red trace) gradually transformed into a sharp peak (blue trace), demonstrating the equilibration process and the near quantitative yield of HUM1.
