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Intramolecular reaction
About: Intramolecular reaction is a research topic. Over the lifetime, 5015 publications have been published within this topic receiving 138213 citations.
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TL;DR: Dendritic catalysts display high activity, affording oxygen, nitrogen, or sulfur-containing seven- or eight-membered ring fused heterocycles in excellent yields and have competitive advantages in that they can be easily recovered by simple filtration in air and reused for up to eight cycles with only a slight loss of activity.
Abstract: Palladium-complexed dendrimers supported on silica were evaluated as catalysts for intramolecular carbonylation reactions. The results showed that dendritic catalysts display high activity, affording oxygen, nitrogen, or sulfur-containing seven- or eight-membered ring fused heterocycles in excellent yields. Moreover, these catalysts have competitive advantages in that they can be easily recovered by simple filtration in air and reused for up to eight cycles with only a slight loss of activity.
129 citations
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TL;DR: A wide range of products, in particular highly functionalized heterocycles, have been synthesised via the Pd-catalysed formation of a C-O bond from allenes via the inter- or intramolecular reaction with a hydroxyl group belonging to an alcohol, a phenol or an acid.
Abstract: The Pd-catalysed formation of a C–O bond from allenes mainly occurs via the inter- or intramolecular reaction with a hydroxyl group belonging to an alcohol, a phenol or an acid. A carbonyl or a carbonate entity can also be involved. In most cases, the formation of the C–O bond is one step of a domino reaction leading also to a C–C or C–N bond, or to another C–O bond. Thus, a wide range of products, in particular highly functionalized heterocycles, have been synthesised. Catalytic cycles have been proposed but the mechanisms often remain speculative.
128 citations
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128 citations
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TL;DR: The expected aziridine was not observed, but rather simultaneous spirocyclization of C(3) and stereoselective syn-acylation at C(2) occurred to give compound 41, whose structure was unequivocally established by an X-ray crystallographic study.
Abstract: Several unsaturated sulfonamides underwent intramolecular aziridination when treated with PhI(OAc)(2), MgO, and catalytic Rh(2)(OAc)(4) to give bicyclic aziridines in excellent yield. Treatment of the resulting azabicyclic sulfonamides in methanol in the presence of p-TsOH resulted in exclusive opening of the aziridine ring at the most substituted position affording six- and seven-membered ring products in high yield. In contrast, the intramolecular aziridination of several cycloalkenyl-substituted carbamates did not require a Rh(II) catalyst and proceeded via an iminoiodinane intermediate. The resulting tricyclic aziridines underwent ring opening when treated with various nucleophiles to give anti-derived products as expected for nucleophilic attack at the three-membered ring. The iodine(III)-mediated reaction of a 3-indolyl-substituted carbamate, however, required a Rh(II) catalyst. The expected aziridine was not observed, but rather simultaneous spirocyclization of C(3) and stereoselective syn-acylation at C(2) occurred to give compound 41, whose structure was unequivocally established by an X-ray crystallographic study. The reaction proceeds in a stepwise manner via a metal-free zwitterionic intermediate which is attacked by a nucleophilic reagent on the same side of the amide anion. Related reactions occurred with both a 2-indolyl- and 3-benzofuranyl-substituted carbamate but with lower stereoselectivity.
127 citations
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127 citations