Building Giant Carbocycles by Reversible C−C Bond Formation

Abstract

We describe a simple way to build giant macrocyclic hydrocarbons by the reversible formation of carbon-carbon bonds. Specifically, extended spirobifluorene-substituted derivatives of Wittig's hydrocarbon were synthesized and found to undergo oligomerization, giving the largest hydrocarbon that has been crystallized and characterized by X-ray diffraction to date.

N‐Substituted Dicyanomethylphenyl Radicals: Dynamic Covalent Properties and Formation of Stimuli‐Responsive Cyclophanes by Self‐Assembly

“…It is expected that am olecule having multiple radical centers as reactive sites can form various self-assembled structures depending on the topology of the monomer,such as periodic networks [16,17] or macrocyclic structures. [18][19][20][21] As af irst step,w et ried to introduce yet another dicyanomethyl radical to 1C and 2C.T PA and Cz having two appended dicyanomethyl radicals, 3 and 4,r espectively,c an possibly construct linear chain structures or cyclic oligomers (Scheme 2). Thep recursors of 3 and 4 with two hydrogen atoms were oxidized by potassium ferricyanideorDDQ.F or the oxidation of 3 2H ,the generation of one colorless spot was observed by TLC,a nd the product was obtained in nearly quantitative yield as ap ale yellow powder after silica gel chromatography.F or the oxidation of 4 2H ,t wo colorless products were obtained in addition to an insoluble blue solid.…”

N‐Substituted Dicyanomethylphenyl Radicals: Dynamic Covalent Properties and Formation of Stimuli‐Responsive Cyclophanes by Self‐Assembly

“…[18][19][20][21] As a first step, we tried to introduce yet another dicyanomethyl radical to 1C and 2C. TPA and Cz having two appended dicyanomethyl radicals, 3 and 4, respectively, can possibly construct linear chain structures or cyclic oligomers (Scheme 2).…”

Formation of a Macrocycles‐in‐a‐Macrocycle Superstructure with All‐gauche Conformation by Reversible Radical Association

“…Supramolecular self-assembly utilizes weak interactions to build complex and highly ordered structures efficiently.T he covalent version of this process was also demonstrated to be efficient for the synthesis of covalent organic frameworks, [1] macrocycles, [2] cages, [3] and two-dimensional (2D) polymers. [4] In most cases,dynamic covalent chemistry (DCC) was applied to ensure an error-correcting assembly process leading to the thermodynamically most stable products.Radical association as al ong-known reversible reaction has recently been reported by Wuest, [5] Seki, [6] and other research groups [7] to be an efficient DCC method for covalent assembly of macrocycles.I nt hese studies,m onomers with double carbon-centered radicals were used. It is reasonable to assume that polymers or 2D frameworks could be formed when using three or multiple radical monomers with planar geometry.H owever,a ssociation of carbon-centered radicals might form C(sp 3 )ÀC(sp 3 )b onds with two possible thermal dynamically stable conformations: gauche and anti.…”