Synthesis of highly hindered oxepins and an azepine from bis-trityl carbenium ions: structural characterisation by NMR and X-ray crystallography

1,2-Bis[bis(4-methoxyphenyl)hydroxymethyl]benzene

“…Neither of these structures involves intramolecular hydrogen bonding, unlike the title compound, and it is clear from the positions of the OH groups that the same is true of the other two previously characterized diols. In our study of diols with a biphenyl unit between the two Csp 3 Ð OH groups, we found intermolecular, but no intramolecular, hydrogen bonds (Carey et al, 2002). Experimental n-Butyllithium (2.2 mol dm À3 in hexanes, 10 ml, 22 mmol) was diluted with THF (20 ml) under nitrogen, and cooled to 195 K. p-Bromoanisole (4.0 g, 21 mmol) was added, whereupon a white precipitate formed; after 10 min, dimethyl phthalate (0.71 g, 3.7 mmol) was added, to give an orange solution.…”

“…Molecules with two diarylmethanol groups close to each other, either with their relative positions ®xed by a rigid framework, as in (1) and (2), or where proximity can be achieved through rotation about a single bond, as in (3), are of interest in two chemical contexts. They are potentially useful as inclusion compounds for host±guest complexes, as in the case of (1) (Toda et al, 1989) and the TADDOLs reported by Seebach (von dem Bussche-Huennefeld et al, 1992;Seebach et al, 1993), and they are potential precursors of bis(diarylmethyl) dications, as in the cases of (1), (2) and (4) (Olah et al, 1976;Hart et al, 1963;Suzuki et al, 1997;Carey et al, 2002).…”

“…We recently prepared diols (3) and (4) as precursors for bis(diarylmethyl) dications for use as protecting groups for primary amines (Carey et al, 2002); in an extension to that work, we prepared compound (5) and now report its crystal structure.…”

(P,M)-1,2,3,9,10,11-Hexamethoxy-5,7-dihydrodibenz[c,e]oxepine and (P,M)-1,11-dimethyl-5,5,7,7-tetraphenyl-5,7-dihydrodibenz[c,e]oxepine

“…All of these values are very similar to those in compounds (I) and (II). In the three structures having no substituents at the peri positions of the biphenyl moiety (Nieger et al, 1998;Carey et al, 2002), the outlined angles are again in similar ranges;¯oor/bow: 39.5± 46.2 ,¯oor/stern: 48.1±52.5 and biphenyl ring plane angle: 46.2±50.4 . Although two of these structures have a similar 5,5,7,7-tetraphenyl substitution pattern to compound (II), the angles between the planes of the biphenyl aromatic rings are no larger than usual, unlike that in (II).…”

2,2,7,7-Tetraphenyl-2,7-dihydrodibenz[c,e]oxepine

“…Since no coordinates from the previous structure determination (Hirano et al, 2004) are available, no comparison between the two structure determinations can be made. However, Carey et al (2002) published the structure of the toluene solvate of the title compound. A least-squares fit of (I) with this solvate (r.m.s.…”