Synthetic Approach Towards Hexaprismane. A Novel Entry to Homosecohexaprismane Skeleton by Cage Enlargement

Abstract

A series of caged 1,4‐diols, 26, 29a/29b, 31, were synthesized from the Diels‐Alder cycloadduct 21 of 1,2,3,4‐tetrachloro‐5,5‐dimethoxycyclopentadiene and 1,4‐benzoquinone. Reduction of enedione 21 with aqueous TiCl3, followed by base‐catalyzed enolization in the presence of acetic anhydride, gave diene 23b, which reacted with maleic anhydride and 1,4‐benzoquinone to produce the corresponding [4+2] cycloadducts 24b and 27, respectively. The adduct 24b was converted to birdcaged 1,4‐diol 26 by photocyclization followed by decarboxylative olefination of resulted caged anhydride 25b. The adduct 27 was photocyclized to cage compound 28, which was aromatized to dihydroquinone 29a by acid‐catalyzed enolization, or benzo‐annulated compound 31 by reduction and dehydration. The birdcaged 1,4‐diols 26 and 31 underwent fragmentation induced by (diacetoxyiodo)benzene to give enediones 38/39 and 41/42, respectively. Photocyclization of 38 and 39 produced the corresponding caged compounds 43 and 44, respectively, possessing homosecohexaprismane skeletons. The corresponding monohydrate 43a of 43 was structurally characterized by single‐crystal X‐ray diffraction.

The Perfluoro Cage Effect: A Search for Electron-Encapsulating Molecules

“…All the perfluorinated prismanes exhibit sizable electron affinities, with the following order across all three functionals (the values in eV shown within parentheses are for OLYP): hexaprismane , (2.15) > pentaprismane , (1.98) > cubane − (1.55) > prismane , (0.97). The ordering suggests a pronounced size effect on the PCE: larger fluorinated cages result in greater stabilization of the encapsulated electron.…”

Photochemical Study of [33](1,3,5)Cyclophane and Emission Spectral Properties of [3n]Cyclophanes (n = 2−6)

“…Recently, attention has been focused on the challenging objective of constructing the higher prismanes, in particular, hexaprismane 11 . Many diverse synthetic strategies have been developed, and significant progress toward the synthesis of hexaprismane 11 has been made. − For example, synthesized secohexaprismane, in which only one C−C bond is missing from hexaprismane 11 …”

The Perfluoro Cage Effect: A Search For Electron-Encapsulating Molecules

“…All the perfluorinated prismanes exhibit sizable electron affinities, with the following order across all three functionals (the values in eV shown within parentheses are for OLYP): hexaprismane 23,24 (2.15) > pentaprismane 25,26 (1.98) > cubane 27−29 (1.55) > prismane 30,31 (0.97). The ordering suggests a pronounced size effect on the PCE: larger fluorinated cages result in greater stabilization of the encapsulated electron.…”