Recent advances in organocatalytic atroposelective reactions

• Henrich Szabados and
• Radovan Šebesta

Beilstein J. Org. Chem. 2025, 21, 55–121, doi:10.3762/bjoc.21.6

• ketoesters 207 and azoalkenes 208 catalyzed by CPA C47 forming the axially chiral products 209 (Scheme 62) [92]. The majority of the products were obtained in very good yields and nearly all possessed excellent enantiomeric purities. Racemization experiments were carried out in m-xylene and toluene. The

Non-covalent organocatalyzed enantioselective cyclization reactions of α,β-unsaturated imines

• Sergio Torres-Oya and
• Mercedes Zurro

Beilstein J. Org. Chem. 2024, 20, 3221–3255, doi:10.3762/bjoc.20.268

• indoles 52 via a (3 + 2) cyclization with azoalkenes 53 catalyzed by chiral phosphoric acid XIV (Scheme 20). This methodology enables the synthesis of a wide scope of pyrroloindolines 54, important privileged polycyclic indolines in high yields (72–99%) and high enantioselectivities (90–99%) [43]. The

• + 3) cycloaddition of 3-alkyl-2-vinylindoles 59 and azoalkenes 53 (Scheme 22). This methodology afforded chiral pyrroloindolines 60 bearing two tetrasubstituted stereogenic centers in good yields (61–96%) and excellent stereoselectivities (all >95:5 dr, 86–99% ee) by using chiral phosphoric acid XVII

• reaction between 1,3-dicarbonyl compounds 68 and azoalkenes 53 (Scheme 26) [48]. This methodology provides access to C1-symmetric biarylamino alcohol derivatives (NPNOL) 69 in a wide scope with good yields (45–89%) and good to excellent atroposelectivities (64–99% ee). In order to explain the reaction

Construction of diazepine-containing spiroindolines via annulation reaction of α-halogenated N-acylhydrazones and isatin-derived MBH carbonates

• Xing Liu,
• Wenjing Shi,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 1923–1932, doi:10.3762/bjoc.19.143

• alternative synthetic methodologies for functionalized 1,2-diazepines has drawn extensive attention [14][15][16][17][18][19][20][21]. One of the most attractive strategies to synthesize the 1,2-diazepine motif represents the [4 + 3] cycloaddition reaction between activated azoalkenes and 1,3-dipolarophiles

Construction of bis-, tris- and tetrahydrazones by addition of azoalkenes to amines and ammonia

• Artem N. Semakin,
• Aleksandr O. Kokuev,
• Yulia V. Nelyubina,
• Alexey Yu. Sukhorukov,
• Petr A. Zhmurov,
• Sema L. Ioffe and
• Vladimir A. Tartakovsky

Beilstein J. Org. Chem. 2016, 12, 2471–2477, doi:10.3762/bjoc.12.241

• alkylations of amines and ammonia with azoalkenes (generated from α-halohydrazones) were demonstrated as an efficient approach to poly(hydrazonomethyl)amines – a novel class of polynitrogen ligands. An intramolecular cyclotrimerization of C=N bonds in tris(hydrazonomethyl)amine to the respective 1,4,6,10

• -tetraazaadamantane derivative was demonstrated. Keywords: azoalkenes; α-halogen hydrazones; heterocage compounds; hydrazone ligands; Michael addition; Introduction Hydrazones are extensively used as key structural units in the design of various functional molecular and supramolecular architectures [1][2][3][4][5

• straightforward methodology based on multiple Michael-type additions of azoalkenes A (generated from α-halogen azacarbonyl precursor 1 [35][36][37][38][39]) to amines or ammonia (Scheme 1). Though the chemistry and synthetic potential azoalkenes A have been a subject of considerable interest in the recent years