Synthesis, x-ray structure and anion binding properties of a cryptand-like hybrid calixpyrrole

The novel cryptand in/out-3, containing two tripyrrolemethane units briged by three 1,3- diisopropylidenbenzene arms was readily synthesized by a convergent three-step synthesis. It binds fluoride by inclusion with excellent selectivity with respect to a number of other tested anions. The structure of the free receptor and that of its fluoride complex were investigated in solution by NMR spectroscopy. The solid state X-ray structure of the free cryptand 3 was also determined

The synthesis of a novel iptycene containing the triphenylene unit

A novel hydrocarbon composed of three 9,10-dihydroanthracene units fused to the three pairs of β positions on a central triphenylene ring has been synthesised. The molecule defines two large cup-shaped cavities lined with π-electron system. Graphi

The regioselective generation of arynes from polyhalogenobenzenes. An improved synthesis of syn- and anti-1,4,5,8,9,12-hexahydro-1,4:5,8:9,12-triepoxytriphenylene

The halogenated benzenes, 1,2,4,5-tetrabromobenzene 6, hexabromobenzene 9, p-dichlorotetrabromobenzene 11, and 1,2-dibromo-4,5-dichlorobenzene 12, were investigated as 1,3-bis-, 1,4-bis-, and 1,3,5-tris-aryne precursors by using alkyllithiums and alkali metal amides as the metalating reagents. The arynes were trapped in Diels-Alder reactions with furan as the diene. The title compounds 3a/b are now readily available in two steps in 7% overall yield from 1,2,4,5-tetrabromobenzene 6. The halogenated benzenes, 1,2,4,5-tetrabromobenzene 6, hexabromobenzene 9, p-dichlorotetrabromobenzene 11, and 1,2-dibromo-4,5- dichlorobenzene 12, were investigated as 1,3-bis-, 1,4-bis, and 1,3,5-tris-aryne precursors by using alkyllithiums and alkali metal amides as metalating reagents. The arynes were trapped in Diels-Alder reactions with furan as the diene. The title compounds 3a/b are now readily available in two steps in 7% overall yield from 1,2,4,5-tetrabromobenzene 6

Calixpyrrole Derivatives: “Multi Hydrogen Bond” Catalysts for γ-Butenolide Synthesis

Calix[4]pyrrole (1), calix[2]m-benzo[4]pyrrole (2), 10α,20β- and 10α,20α- bis(4-nitrophenyl)-calix[4]pyrroles 3 and 4, respectively, were found to exhibit various organocatalytic activities in the diastereoselective vinylogous addition reaction of 2-trimethylsilyloxyfuran (TMSOF, 7) to aldehydes. The γ-hydroxybutenolide products are obtained in fairly good yields and with moderate diastereoselectivity. The structures of the catalysts, as well as the reaction conditions, strongly influence the efficiency of the reaction

Acenaphane derivatives from furan macrocycles

The macrocycle 1 reacts with benzynes to give the Diels-Alder tetra-adduct 11 as a single isomer in good yields. Its mode of formation has now been investigated and its stereochemistry confirimed by X-ray crystallographic analysis. Benzynes react with 1 stepwise with high regio and facial selectivity. Only the mono-adduct 2 could be aromatised to the furanaphthaphane 17, and its conformational behaviour has been investigated by means of dynamic 1H NMR spectroscopy and by single crystal X-ray analysis. The tetra-adduct 11 exhibits molecular recognition in the solid state selectively entrapping p-xylene when crystallised from a mixture of xylenes. Multiple aryne cycloaddition to 1 occurs with high facial and regio selectivity giving single bis- tris- and tetra-addition products. Only the mono-adduct could be aromatised to give 17, whose conformational behaviour has been investigated by means of dynamic 1H NMR. Both 11 and 17 have been studied by X-ray crystallography. The tetra-adduct 11 selectively entraps p-xylene when crystallised from a mixture of xylenes

Efficient Organocatalysis with a Calix[4]pyrrole Derivative

The 10a,20b-bis(4-nitrophenyl)-calix[4]pyrrole was found to act as an effective organocatalyst for the hetero Diels–Alder reaction of Danishefsky’s diene with aromatic aldehydes. This discovery is the first reported case of a calixpyrrole that exhibits organocatalytic activity