1338698-45-5Relevant academic research and scientific papers
Gold-Catalyzed Regiospecific Annulation of Unsymmetrically Substituted 1,5-Diynes for the Precise Synthesis of Bispentalenes
Tavakkolifard, Sara,Sekine, Kohei,Reichert, Lisa,Ebrahimi, Mina,Museridz, Ketevan,Michel, Elena,Rominger, Frank,Babaahmadi, Rasool,Ariafard, Alireza,Yates, Brian F.,Rudolph, Matthias,Hashmi, A. Stephen K.
, p. 12180 - 12186 (2019)
Precise control of the selectivity in organic synthesis is important to access the desired molecules. We demonstrate a regiospecific annulation of unsymmetrically substituted 1,2-di(arylethynyl)benzene derivatives for a geometry-controlled synthesis of linear bispentalenes, which is one of the promising structures for material science. A gold-catalyzed annulation of unsymmetrically substituted 1,2-di(arylethynyl)benzene could produce two isomeric pentalenes, but both electronic and steric effects on the aromatics at the terminal position of the alkyne prove to be crucial for the selectivity; especially a regiospecific annulation was achieved with sterically blocked substituents; namely, 2,4,6-trimetyl benzene or 2,4-dimethyl benzene. This approach enables the geometrically controlled synthesis of linear bispentalenes from 1,2,4,5-tetraethynylbenzene or 2,3,6,7-tetraethynylnaphthalene. Moreover, the annulation of a series of tetraynes with a different substitution pattern regioselectively provided the bispentalene scaffolds. A computational study revealed that this is the result of a kinetic control induced by the bulky NHC ligands.
Gold-Catalyzed Cyclisation by 1,4-Dioxidation
Claus, Vanessa,Molinari, Lise,Büllmann, Simon,Thusek, Jean,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
supporting information, p. 9385 - 9389 (2019/04/30)
Amide-substituted diynes were cyclized in the presence of a cationic gold catalyst and an external nucleophile leading to 1-indenones and 1-iminoindenones. The electron-donating features of the nitrogen atom enable the formation of a reactive ketene iminium ion, which can be trapped by either diphenyl sulfoxide or anthranil as nucleophiles in a subsequent oxidation step, providing substituted inden-1-on-3-carboxamides.
Insights into the Gold-Catalyzed Propargyl Ester Rearrangement/Tandem Cyclization Sequence: Radical versus Gold Catalysis - Myers-Saito- versus Schmittel-Type Cyclization
Rettenmeier, Eva,Hansmann, Max M.,Ahrens, Alexander,Rübenacker, Katharina,Saboo, Tapish,Massholder, Joy,Meier, Christian,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
supporting information, p. 14401 - 14409 (2015/10/05)
A detailed study of the gold-catalyzed tandem 1,3-carboxy migration/allene-enyne cycloisomerization was undertaken. It was found that after the initial allene formation the selectivity of the reaction is strongly influenced by the polarization of the remaining alkyne. Depending on the substitution pattern of the starting diynes, either a Schmittel- or a Myers-Saito-type cyclization was triggered. The 6-endo-dig Myers-Saito-type cyclization gave access to benzo[b]fluorenes, while the Schmittel pathway (5-exo-dig) delivered benzofulvenes as final products. In special cases a yet unknown pathway was opened by the ambiphilic nature of the allene moiety. In these cases completely different products were obtained by the nucleophilic attack of the alkyne moiety onto the allene that can also act as an electrophile. Mechanistic studies revealed that diradical pathways can be ruled out for this type of tandem cyclization reactions and it is shown that both steps of the reaction cascade are catalyzed by the gold complex.
