605-55-0Relevant articles and documents
In-Fjord Substitution in Expanded Helicenes: Effects of the Insert on the Inversion Barrier and Helical Pitch
Suárez-Pantiga, Samuel,Redero, Pablo,Aniban, Xaiza,Simon, Martin,Golz, Christopher,Mata, Ricardo A.,Alcarazo, Manuel
, p. 13358 - 13366 (2021)
A series of expanded helicenes of different sizes and shapes incorporating phenyl- and biphenyl-substituents at the deepest part of their fjord have been synthesized via sequential Au-catalyzed hydroarylation of appropriately designed diynes, and their racemization barriers have been calculated employing electronic structure methods. These show that the overall profile of the inversions (energies, number of transition states and intermediates, and their relative position) is intensively affected by the interplay of steric and attractive London dispersion interactions. Hence, in-fjord substitution constitutes an additional tool to handle the mechanical properties in helicenes of uncommonly large diameter. The photochemical characterization of the newly prepared helical structures is also reported.
Experimental and theoretical studies on polar Diels-Alder reactions of 1-nitronaphathalene developed in ionic liquids
Mancini, Pedro M. E.,Rosa, Claudia D. Della,Ormachea, Carla M.,Kneeteman, Maria N.,Domingo, Luis R.
, p. 13825 - 13834 (2013/08/23)
The reactions between 1-nitronaphthalene 1 and two nucleophilic dienes, Danishefskys diene 2 and 1-trimethylsilyloxy-1,3-butadiene 3, to yield phenanthrenols 7 and 8 developed in protic and aprotic ionic liquids (ILs) with an imidazolium cation base permit to conclude that the reactions occur in better experimental conditions than in molecular solvents. The yields obtained with protic ILs are better than those observed with aprotic ILs. In this sense, the higher yields obtained with aprotic ILs, (working at 60°C, 48 h) are comparable with the lower yields observed in protic ILs (60°C, 24 h). DFT calculations for the reaction of 1-nitronaphthalene 1 with diene 3, in the absence and in the presence of tetrafluoroborate of 1-metilimidazolium [HMIM][BF4] as protic ILs, indicate that this reaction is a domino process that comprises two consecutive processes: i) a polar Diels-Alder (P-DA) reaction between 1 and 3, and ii) an elimination of nitroso acid 5 to yield dihydrophenanthrene 11. Thermodynamic calculations indicate that while the first reaction is the rate-determining step of this domino process, the nitroso acid elimination is the driving force responsible for the formation of dihydrophenanthrene 11. Implicit and explicit solvent effects indicate that while the hydrogen bond formation between HMIM and one oxygen atom of the nitro groups favour the two reactions, implicit solvent effects modelled by PCM decelerate the P-DA reaction by a large solvation of reagents. Finally, DFT analysis of reagents offers an explanation of the catalytic role of protic ILs in these P-DA reactions.
Intramolecular gold(III) catalysed Diels-Alder reaction of 1-(2-furyl)-hex-1-en-5-yn-3-ol derivatives: A short and generalised route for the synthesis of hydroxyphenanthrene derivatives
Samanta, Khokan,Kar, Gandhi K.,Sarkar, Achintya K.
supporting information; experimental part, p. 1376 - 1379 (2012/04/04)
Gold(III) catalysed intramolecular Diels-Alder reaction of various 1-(2-furyl)-hex-1-en-5-yn-3-ol derivatives has been studied to synthesise hydroxyphenanthrenes and other polynuclear aromatic hydroxyl compounds. The required precursors were synthesised by indium mediated propargylation of suitable β-furyl-α,β-unsaturated aldehydes.
