Unexpected chiral vicinal tetrasubstituted diamines via borylcopper-mediated homocoupling of isatin imines

• Marco Manenti,
• Leonardo Lo Presti,
• Giorgio Molteni and
• Alessandra Silvani

Beilstein J. Org. Chem. 2022, 18, 303–308, doi:10.3762/bjoc.18.34

• diffraction analysis and proved to be single diastereoisomers and atropisomers. A plausible mechanism for the one-pot Cu(II)-catalyzed Bpin addition to the isatin-derived ketimine substrate and subsequent homocoupling is described. Keywords: atropoisomer; bis(pinacolato)diboron; 3,3′-bisoxindole; N-tert

• the one away from the bulky auxiliary t-Bu group. The presence of two NH-SOt-Bu substituents, preventing the free rotation around the C3–C3’ bond, ensures the optical activity of the molecule, in accordance with the presence of a single atropoisomer (absence of any pseudo-mirror plane), as also

Calix[6]arene-based atropoisomeric pseudo[2]rotaxanes

• Carmine Gaeta,
• Carmen Talotta and
• Placido Neri

Beilstein J. Org. Chem. 2018, 14, 2112–2124, doi:10.3762/bjoc.14.186

• is the most populated in solution, consequently, the threading of this conformation, besides being faster, it is also favored by its abundance in solution. The greater thermodynamic stability of the 2+1cone atropoisomer over the 2+11,2,3-alt one, was confirmed by DFT calculations at the B3LYP/6-31G(d

• ). Differently, in the DFT-optimized structure of 2+11,2,3-alt atropoisomer (Figure 7, right), the stabilization of the 2+11,2,3-alt atropoisomer was brought, principally by two H-bonding interactions between the ammonium group of 2+ and the oxygen atoms of anti-oriented phenol rings of 1 with an average N···O

• distance of 3.05 Å and a narrower N–H···O angle of 167.1°. Single-point calculations at the B3LYP/6-31G(d,p) level of theory using Grimme’s dispersion corrections (IOp(3/124=3)), indicated that the 2+1cone atropoisomer was more stable than the 2+11,2,3-alt one by 2.4 kcal mol−1. At this point, it is worthy