[7]Metacyclophane and its 13-bromo derivative

Molecular Structures of THF‐Solvated Alkali‐Metal 2,2,6,6‐Tetramethylpiperidides Finally Revealed: X‐ray Crystallographic, DFT, and NMR (including DOSY) Spectroscopic Studies

“…The flip barrier20,21 of 2,6‐ ansa ‐pyridines is, in the case of a heptamethylene chain, only moderately smaller than that of the carba‐analogous biphenyl (9.0 vs. 11.5 kcal/mol for Z = N and CH, respectively; Table 1). 22,23 Also, in the case of some metaparacyclophanes containing two CH 2 SCH 2 links between the two aryl rings, the differences are quite small 24,25…”

Revisiting cyclophanes: experimental characterization and theoretical elucidation of the chain length influence on their structure and reactivity

“…12 In the case of the synthesis of [n]metacyclophanes (n = 6-8), several methods starting with thermal rearrangement have been proposed. In each case, this first step is followed by aromatization of [n.2.1]-substituted propellanes; by acid-catalyzed rearrangement of [6]paracyclophanes; [13][14][15] by intramolecular Diels-Alder reaction and subsequent dehydrogenation; [16][17][18] or by cycloaddition of a m-xylylene diradical with 1,3-dienes. 19,20 In contrast, [5]metacyclophanes and their derivatives have been synthesized by opening [5.3.1]propellanes under mild conditions.…”

How Space‐Filling Is a Pyridine Lone Pair?

“…With other topologies, it is not always easy to predict the space requirements of pyridines relative to benzenes. This can be deduced from the landmark work of Boekelheide, Vögtle, and Nozaki and their co-workers [20][21][22][23]29,30] ( Table 1).…”

“…[22,23] Also, in the case of some metaparacyclophanes containing two CH 2 SCH 2 links between the two aryl rings, the differences are quite small. [24,25] However, the activation energies vary by more than 10 kcal/mol when a 2,6-pyridinediyl or a 1,3-phenylene ring is incorporated into the oligomethylene chain (14.8 vs. Ͼ27 kcal/mol; Table 1) [26,27] and by at least 7 kcal/mol for the dithia analogues (Ͻ13.6 vs. 20.5 kcal/mol; Table 1).…”