1,2-Dibenzoyl-3,4-bis(4-methoxyphenyl)cyclobutane

Abstract

The title compound, C32H28O4, crystallizes with two conformers, α and β, in the asymmetric unit. In both conformers, the benzo­yl and methoxy­phen­yl groups are in cis positions. The cyclo­butane rings are puckered, with average absolute torsion angles of 10.8 (2) and 11.4 (1)° for conformers α and β, respectively. The crystal packing is stabilized by weak inter­molecular C—H⋯O hydrogen bonds and benzene π–π inter­actions.

Cation−π Controlled Solid-State Photodimerization of 4-Azachalcones

“…Irradiation of the crystals of 1b produced the syn HH dimer 3a in 67% yield as expected from the preorganized head-to-head orientation (Table , entry 3). The structures of 3a and the three minor isomers were assigned by comparison of the 1 H NMR spectra with those for the reported dimers of the 4-methoxychalcones. , …”

“…The structures of 3a and the three minor isomers were assigned by comparison of the 1 H NMR spectra with those for the reported dimers of the 4-methoxychalcones. 12b, 14 The effectiveness of the cation-π interaction as a tool to control the orientation of the molecules was demonstrated by changing the packing mode of 1b. While 1b prefers a head-tohead arrangement in the crystal as described above, the conversion of 1b into the HCl salt caused a change in the packing mode to a head-to-tail orientation, in which the separations of the two neighboring rings and two double bonds were 3.654 and 3.789 Å, respectively (Figure 1d).…”

1,2-Bis(4-nitrobenzoyl)-3,4-bis(4-nitrophenyl)cyclobutane

“…For background and details of the 'topochemical principle' for [2 + 2] photoreactions in the solid state, see: Schmidt (1971); MacGillivray et al (2000); Toh et al (2005); Papaefstathiou et al (2001). For crystal structures of related compounds, see: Steyl et al (2005) and Toda et al (1998).…”