Formation of an unexpected 3,3-diphenyl-3H-indazole through a facile intramolecular [2 + 3] cycloaddition of the diazo intermediate

• Andrew T. King,
• Hugh G. Hiscocks,
• Lidia Matesic,
• Mohan Bhadbhade,
• Roger Bishop and
• Alison T. Ung

Beilstein J. Org. Chem. 2019, 15, 1347–1354, doi:10.3762/bjoc.15.134

• structures stabilised by multiple tert-butyl groups [20][21], multi-ring cage hydrocarbons [22][23], and linear alkanes [22][23]. The interaction was found to be attractive in all these cases, and computational justifications have been published [21][23]. It, therefore, appears probable that, despite their

Reciprocal polyhedra and the Euler relationship: cage hydrocarbons, C_nH_n and closo-boranes [B_xH_x]²⁻

• Michael J. McGlinchey and
• Henning Hopf

Beilstein J. Org. Chem. 2011, 7, 222–233, doi:10.3762/bjoc.7.30

• described. Keywords: cage hydrocarbons; high symmetry; reciprocal polyhedra; Review Platonic polyhedra and the Euler relationship The Platonic solids have long fascinated geometers, artists and chemists alike. Molecular analogues of the tetrahedron (P4, B4Cl4, Si4t-Bu4), octahedron ([B6H6]2−), cube (C8H8

• , [B6H6]2− has 7 skeletal electron pairs and is three-dimensionally aromatic. In contrast, in the CnHn cages the number of skeletal electron pairs equals the number of edges. In terms of the Euler equation (V + F = E + 2), for cage hydrocarbons, 2E = 3V, as exemplified by cubane, C8H8, which has 12 edges

• original concept and propose that other highly symmetrical cage hydrocarbons of the CnHn type might have closo-borane counterparts. Indeed, Lipscomb and Massa have discussed the structures of borane analogues of fullerenes [52][53] and even of nanotubes [54]. In particular, they proposed that C60 (V, E, F