Aromatic C–H bond functionalization through organocatalyzed asymmetric intermolecular aza-Friedel–Crafts reaction: a recent update

• Anup Biswas

Beilstein J. Org. Chem. 2023, 19, 956–981, doi:10.3762/bjoc.19.72

• generating a complex molecular topology of 2,3-disubstituted indoles bearing both axial and central chirality. The aza-Friedel–Crafts reaction would allow the nucleophile to selectively attack the C=N plane of the electrophile as directed by a triple hydrogen-bonded complex between the catalyst and the

• electrophilic substitution also gave a quaternary aza-stereocenter in the pyrazolone moiety. Axial chirality associated with central chirality in the product structures was influenced by chiral phosphoric acid catalyst P23. To freeze the C–C bond rotation, the pyrazole moiety in 99 required sterically demanding

Recent advances in the asymmetric phosphoric acid-catalyzed synthesis of axially chiral compounds

• Alemayehu Gashaw Woldegiorgis and
• Xufeng Lin

Beilstein J. Org. Chem. 2021, 17, 2729–2764, doi:10.3762/bjoc.17.185

• central chirality information to the axial chirality to give the chiral biaryldiols (Scheme 3) [14]. In 2013, Akiyama and co-workers described the enantioselective preparation of multisubstituted biaryls by the desymmetrization strategy, which was further enhanced by the subsequent asymmetric reaction

• enantioselectivity (91:9 to 98:2 er, Scheme 15) [65]. In addition, the authors also succeeded in preparing naphthylindoles 46, which exhibit both axial and central chirality, through the addition reaction of racemic naphthylindoles 42 and o-hydroxybenzyl alcohols 45 using chiral phosphoric acid CPA 13. This reaction

• also achieved the first catalytic asymmetric construction of axially chiral 3,3’-bisindole scaffolds 49 bearing both axial and central chirality by employing the CPA-14-catalyzed asymmetric addition reaction of 2-substituted 3,3’-bisindoles 47 to isatin-derived 3-indolylmethanols 48. The isatin-derived

Design and synthesis of quasi-diastereomeric molecules with unchanging central, regenerating axial and switchable helical chirality via cleavage and formation of Ni(II)–O and Ni(II)–N coordination bonds

• Vadim A. Soloshonok,
• José Luis Aceña,
• Hisanori Ueki and
• Jianlin Han

Beilstein J. Org. Chem. 2012, 8, 1920–1928, doi:10.3762/bjoc.8.223

• *) and (Ra*,Ph*,Rc*) occurs by intramolecular trans-coordination of Ni–NH and Ni–O bonds providing a basis for a chiral switch model. Keywords: axial chirality; central chirality; chiral switches; coordination bonds; functional materials; helical chirality; modular structural design; molecular devices

• expect, these desired structural and stereochemical considerations can be seriously compromised by the presence of central chirality in the starting ligand 4. For instance, application of racemic ligands 4 will give rise to at least four diastereomeric products rendering the designed diastereomeric

• instance, the torsion angle C(19)–N(3)–C(20)–C(21) of 32.0(3)° sets the element of helical chirality, while the axial chirality is located through the N(1)–C(8) bond with the torsion angle C(9)–N(1)–C(8)–C(7) of −139.5(2)°. The central chirality is located on N(2) as, coordinated to Ni(II), nitrogen is