The synthesis of unique structures of tetra-crown ethers through Michael addition

Synthesis and Crystal Structure Determination of [H2‐cryptand 222](Br3)2: A Unique Tribromide Catalyst for the Catalytic Chemoselective N‐Boc Protection of Amines

“…N-Boc pro- 2 In a round-bottomed flask (100 mL) equipped with a magnetic stirrer, bromine (0.494 g, 3.1 mmol) was added to a solution of cryptand 222 (0.376 g, 1 mmol) in ethanol (30 mL) and the mixture was stirred for 0.5 hour. Filtration through a sintered glass funnel gave a fine yellow powder [0.81 g, 95% yield], which was recrystallized from CH 3 The solution was stirred at room temperature for one minute. The amine (1 mmol) was then added and the solution was stirred at room temperature for the appropriate time (see Table 2).…”

“…Crown ether moieties are popular host compounds in host-guest chemistry and these ligands have shown a remarkable ability to form strong complexes with organic and inorganic cations [1][2][3] or anions, 4,5 selectively. Among the crown ethers, cryptand 222, a macrobicyclic compound, has been used in a variety of applications including the formation of a conductometric mercury [II] sensor based on poly aniline, 6 the encapsulation of alkali metals, especially K + , [7][8][9] use as an acceptor ligand for the formation of complexes containing 7,7,8,8-tetracyanoquinodimethane (TCNQ), 10 extraction of uranium(VI), 11 exchanging the cations of micas 12 and extraction of copper(II) with erythrosine B.…”

Synthesis, Characterization, and Binding Properties of Novel Penta-Crown Ethers

“…Multi-site crown ethers have attracted considerable attention due to their fascinating structures and coordination properties with guest cations [1][2][3][4][5][6][7][8][9][10][11][12] and their application in synthetic, host-guest, and supramolecular chemistry. [13][14][15][16][17][18][19][20] A multi-site crown ether and some of its derivatives have found applications in quite widespread areas; their main application was their use as ionophores and host compounds.…”

“…When the cation size exceeds that of the crown ether unit cavity such as in the 'butterfly crown ethers', [23][24][25][26] it may form a host/guest 2:1 sandwich-type complex. [23][24][25][26][27][28][29][30][31] In our previous work, [17][18][19][20] we found an efficient synthetic approach to tris-, tetra-and penta-crown ethers by Michael addition using multi-acrylates as the linker. The triacrylate of trimethylolpropane triacrylate (TMPTA) has proven to be a useful linker to prepare multi-site crown ethers.…”

Synthesis of Novel Tris-Crown Ether Structures

“…It was reported 38,39 that TMPTA can easily react with amines through Michael addition. We have succeeded 40 in using this idea to synthesize tetra-crown ethers. TMPTA has the advantage of low viscosity and high solubility in general organic solvents.…”