In situ alkylation of N-heterocycles in organic templated cuprous halides
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Updated: Jun 15, 2026

Preparation of a Corannulene-functionalized Hexahelicene by Copper(I)-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
Published on: September 18, 2016
Juan-Juan Hou1, Shi-Li Li, Cui-Rui Li
1School of Chemistry & Material Science, Shanxi Normal University Linfen, Shanxi, 041004, China.
Abstract:
Five new cuprous halides formulated as [etpy][Cu(3)I(4)] 1, [mepy][Cu(2)Br(3)] 2, [mepy][Cu(2)I(3)] 3 [dmebpp][Cu(7)Br(9)] 4 and [dmeDABCO](4)[Cu(8)I(16)] 5 (etpy = N-ethylpyridyl; mepy = N-methylpyridyl; dmebpp = N,N'-dimethyl-1,3-bis(4-pyridyl)propane; dmeDABCO = N,N'-dimethyl-1,4-diazabicyclo-[2.2.2]octane) have been prepared by solvothermal reactions of a copper source, halides and N-heterocyclic ligands in alcoholic solution. 1 contains an unprecedented trigonal two-dimensional cuprous halide layer Cu(3)I(4)(-) constructed from trimeric Cu(3)I(8) units via sharing peripheral mu(3)-iodines; isostructural 2 and 3 contain infinite Cu(2)X(3)(-) chains in which the copper atoms are arranged into a ladder; 4 is composed of novel twofold helical cuprous halide chains Cu(7)Br(9)(2-) built up by CuBr(4) and CuBr(3); 5 contains an infinite edge-sharing tetrahedral chain with a periodic sequence of eight CuI(4) tetrahedra. In situ alkylation reactions of N-heterocycles with alcohols generated organic cationic templates, which played an important role in the control of the structures of anionic cuprous halides. A possible alkylation mechanism of N-heterocycles in the system has been proposed. The fluorescence properties of 1 and 4 were investigated. Time-dependent density functional theory (TD-DFT) calculations were carried out on the excited electronic states 1 of in order to understand the emission mechanism.
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Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
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Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
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