Mixing <i>O</i>‑Containing and <i>N</i>‑Containing Directing Groups for C–H Activation: A Strategy for the Synthesis of Highly Functionalized 2,2′-Biaryls

A strategy combining <i>O</i>- and <i>N</i>-containing directing groups has been developed for the synthesis of 2,2′-biaryl via Pd-mediated C–H bond activation and oxidative coupling. This new transformation may proceed through a mechanism involving Pd­(II) and Pd­(IV) intermediates. We found the use of PTSA and HFIP to be critical for the reaction and suggest that these reagents could serve as efficient ligands for this C–C bond formation. This methodology provides broad functional group tolerance, excellent reactivity, and high yields

Crystallizable and Tough Aliphatic Thermoplastic Polyureas Synthesized through a Nonisocyanate Route

A simple nonisocyanate route for synthesizing crystallizable and tough aliphatic thermoplastic polyureas (TPUreas) is described. Melt transurethane polycondensation of diethylene glycol bis­(3-aminopropyl) ether with bis­(hydroxyethyl) hexanediurethane and bis­(hydroxyethyl) isophoronediurethane was conducted at 170 °C under a reduced pressure of 3 mmHg, and a series of TPUreas were prepared. The TPUreas were characterized by GPC, FT-IR, ¹H NMR, ¹³C NMR, 2D ¹³C–¹H HSQC NMR, DEPT-135 ¹³C NMR, DSC, TGA, wide-angle X-ray scattering, atomic force microscopy, and tensile tests. The TPUreas exhibited an <i>M</i>_n up to 12 000 g/mol, an <i>M</i>_w up to 17 600 g/mol, <i>T</i>_g between 2.8 and 18.1 °C, <i>T</i>_m from 140.5 to 149.8 °C, initial decomposition temperature of over 278.4 °C, and tensile strength up to 37.81 MPa with elongation at break of 691.25%. TPUreas with high <i>T</i>_m, good tensile strength, and good toughness were prepared through a nonisocyanate route