Interactions and reactions in some 2,2′-disubstituted biphenyls—an open or shut case

Interaction, bond formation or reaction between a dimethylamino group and an adjacent alkene or aldehyde group in aromatic systems controlled by remote molecular constraints

“…Thus, there is a long Me 2 N•••CHO interaction in 11 (2.989(2) Å), but formation of a zwitterion with a six-membered ring in 12, with a Me 2 N + -C(CN) 2bond (1.586(3) and 1.604(3) Å). 13 Recently we demonstrated that for peri-naphthalenes containing a Me 2 N-group adjacent to a -CH=C(CN) 2 group, the Me 2 N•••C=C separations can be controlled by substituents at the opposite pair of peri-positions, e.g. an ethylene bridge as in acenaphthene 13 opens up the separation between the two groups, while two peri-phenyl groups, which repel each other, reduces the separation in 14.…”

“…A peri-disubstituted acenaphthene system has been used to investigate nucleophilic attack at silicon 15 and to prepare frustrated lone pair systems. 16 that only 21 has a bond between the peri-groups, since there is no low field 13 C NMR resonance at ca. 160 ppm for the peri-alkene carbon but a signal instead at 89.8 ppm.…”

“…The Me 2 N-C bond formed between peri-substituents in 19 is 1.6719( 14) Å long and the former alkene bond is now 1.4543( 14) Å. In the two independent molecules of the biphenyl derivative 12 13 where a dimethylamino group has added to an alkenedinitrile to form This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. Study of a crystal of the chloroform solvate of 21, the Knoevenagel product formed from the diphenyl aldehyde 17 with cyclohexan-1,3-dione, showed that it also adopts a closed structure, as does its analogue without peri-phenyl groups 25.…”

Modelling of an aza-Michael reaction from crystalline naphthalene derivatives containing peri–peri interactions: very long N–C bonds?

“…The results of a reaction between this pair of groups to form a zwitterion has been observed in crystals of the corresponding biphenyl system 7, with new Me 2 N-C bonds of 1.586 3and 1.604(3) Å in the two independent molecules. 21 In this case the reaction involves the formation of a less strained ring than in the naphthalene series.…”

O(−)⋯C interactions and bond formation in 1-naphtholate anions with peri-located electrophilic carbon centres

“…in which the alkenes are activated by two in-plane carbonyl groups were deprotonated with mild bases such as DABCO or DMAP to give stable anions[30][31][32] respectively with an O-C bond between the peri groups and the negative charge stabilised by the two carbonyl groups. In contrast, the naphthol with the less electrophilic ethenedinitrile group 22, like the ketones 9 and 11, was not deprotonated with DABCO or DMAP, but was partially deprotonated by the stronger guanidine base TMG.It was completely deprotonated by sodium hydride, leading to the purple anion 29, formed by addition of the oxygen anion to the double bond, which decomposed after several hours.…”