Showing papers on "Intramolecular reaction published in 2014"
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
TL;DR: According to density functional theory calculations, the gold-catalyzed retro-Buchner process occurs stepwise, although the two carbon–carbon cleavages occur on a rather flat potential energy surface.
Abstract: The fate of the aryl gold(I) carbenes generated by retro-Buchner reaction of ortho-substituted 7-aryl-1,3,5-cycloheptatrienes is dependent on the constitution of the ortho substituent. Indenes and fluorenes are obtained by intramolecular reaction of highly electrophilic gold(I) carbenes with alkenes and arenes. According to density functional theory calculations, the gold-catalyzed retro-Buchner process occurs stepwise, although the two carbon–carbon cleavages occur on a rather flat potential energy surface.
89 citations
TL;DR: The intramolecular reaction of dialkyl peroxides with carbanions, generated via chemoselective metal-heteroatom exchange or deprotonation, provides a new approach to cyclic ethers by enabling a one-step annelation to form oxaospirocycles.
Abstract: The intramolecular reaction of dialkyl peroxides with carbanions, generated via chemoselective metal-heteroatom exchange or deprotonation, provides a new approach to cyclic ethers. Applied in tandem with C–C bond formation, the strategy enables a one-step annelation to form oxaospirocycles.
49 citations
TL;DR: A simple, iron-based catalytic system allows for the inter- and intramolecular arylation of unactivated secondary alcohols and provides an enantioenriched product for the intramolescular reaction, thereby offering a convenient approach to nonracemic products.
41 citations
TL;DR: An efficient gold(I)-catalyzed alkenylation of β-alkyne-substituted pyrroles is reported, and the intermolecular reaction with alkynes provides functionalized pyrrole derivatives.
37 citations
TL;DR: In this article, a general strategy to synthesize bridged polycyclic molecules is presented via a cascade reaction initiated by rhodium carbene formation, followed by a transannular C-H bond insertion.
20 citations
TL;DR: The product of this reaction, generated by the ring-opening insertion of dioxaphospholane moieties into lutetium-carbon bonds, was characterized by multinuclear NMR spectroscopy and single crystal X-ray diffraction.
Abstract: Geometrically constrained dioxaphospholane rings were incorporated into a bis(phosphinimine)carbazole ligand (HL) in an effort to generate an ancillary ligand system that is capable of supporting reactive lutetium alkyl functionalities and resistant to cyclometalation reactivity. This new ligand was used to prepare a lutetium dialkyl species, LLu(CH2SiMe3)2; however, the complex exhibited low thermal stability at ambient temperature. This dialkyl compound was found to be highly susceptible to a cascading inter- and intramolecular reaction that resulted in the sole formation of an asymmetric bimetallic tetraalkoxide complex. The product of this reaction, generated by the ring-opening insertion of dioxaphospholane moieties into lutetium-carbon bonds, was characterized by multinuclear NMR spectroscopy and single crystal X-ray diffraction.
16 citations
TL;DR: In this article, a functionalized spiro-tetrahydro-β-carbolines were formed by an efficient gold(I)-catalyzed rearrangement reaction of alkynylaziridine indoles.
14 citations
TL;DR: The catalytic dehydrogenation mechanism of ammonia borane (NH3BH3, AB) by Ni N-heterocyclic carbene (NHC) complexes has been investigated by density functional theory as discussed by the authors.
12 citations
TL;DR: A versatile synthetic route to new 4-quinolone-based polycyclic systems is described in this article, where TFA-catalyzed intramolecular reaction of N-unsubstituted quinolone 2-carboxylic acid amides gives structurally diverse compounds, depending on the length of the chain.
11 citations
TL;DR: An expedient methodology to synthesize macrocyclic compounds in one step based on the Nicholas reaction is disclosed, generating two new C3-symmetric hexasubstituted benzene structures suitable for molecular recognition purposes.
TL;DR: An aluminum triflate-catalyzed intramolecular reaction sequence involving protonation and Mannich-like nucleophilic addition of indoles toward the concise construction of the tetrahydropyrido[1,2-a]indol-6-one skeleton is reported in this paper.
Abstract: An aluminum triflate-catalyzed intramolecular reaction sequence involving protonation and Mannich-like nucleophilic addition of indoles toward the concise construction of the tetrahydropyrido[1,2-a]indol-6-one skeleton is reported. This new reaction pattern employs a carbon atom as nucleophile to form a C-C bond which bears one or even two quaternary carbons and leads to the dearomatization of indoles with high atom economy.
TL;DR: In this paper, an α-nitro-δ-keto-nitrile readily forms the corresponding ammonium salt immediately upon treatment with an amine, when the amine liberated under equilibrium, the nucleophilic amine and the electrophilic keto nitrile come close to each other to afford so-called an intimate pair.
TL;DR: In this article, self-assembled phosphorus ligands were synthesized and used in the rhodium complex catalyzed hydroformylation-Wittig reaction of homoallylic olefins under optimized condition.
TL;DR: A versatile synthetic procedure is described to prepare the benzimidazole-fused 1,2,4-thiadiazoles 2a–c via a methanesulfonyl chloride initiated multistep cyclization involving the intramolecular reaction of an in-situ generated carbodiimide with a thiourea unit.
Abstract: A versatile synthetic procedure is described to prepare the benzimidazole-fused 1,2,4-thiadiazoles 2a–c via a methanesulfonyl chloride initiated multistep cyclization involving the intramolecular reaction of an in-situ generated carbodiimide with a thiourea unit. The structure of the intricate heterocycle 2a was confirmed by single-crystal X-ray analysis and its mechanism of formation supported by DFT computations.
TL;DR: Acyl group migration from N to C in aziridine-2,2-carboxylates takes place in deprotonation reactions and, as a result, Aziridine 2,2,dicarboxylate are formed as mentioned in this paper.
TL;DR: In this paper, the pseudo-intramolecular transacylation reaction efficiently proceeds like an intramerolecular reaction, even though it is actually an intermolecular one.
Abstract: The pseudo-intramolecular transacylation reaction efficiently proceeds like an intramolecular reaction, even though it is actually an intermolecular reaction. We have obtained valuable insights by monitoring the reaction by 1H NMR spectroscopy.
TL;DR: Amination of tertiary and secondary alcohols using aqueous ammonia as nitrogen source was carried out by a process with recyclable intramolecular reaction of 1,8-naphthosultone, which lead to α-branched primary amines as discussed by the authors.
TL;DR: It is found that α-amino acid amide derivatives of 2-aminobenzothiazoles undergo a time-dependent, thermal rearrangement in which the amine group attacks the 2-position carbon of the thiazole ring to form a 5,5-spiro ring system.
TL;DR: The enantiospecific total synthesis of the δ-lactonic marine natural product (+)-tanikolide (1), isolated from Lyngbya majuscula, was achieved using a [2, 3]-Meisenheimer rearrangement as the key reaction as mentioned in this paper.
Abstract: The enantiospecific total synthesis of the δ-lactonic marine natural product (+)-tanikolide (1), isolated from Lyngbya majuscula , was achieved using a [2,3]-Meisenheimer rearrangement as the key reaction. During this rearrangement, we discovered that the allylic amine N-oxide could direct the m-CPBA double-bond epoxidation to the syn position. The resulting syn product 8 underwent epoxide ring opening under the m-CBA conditions to give the five- and six-membered cyclic ether amine N-oxides, which we further treated with Zn and conc. HCl to obtain the reduced bisbenzyl tertiary amines 23 and 22, respectively. When 23 and 22 were treated with trichloroisocyanuric acid (TCCA) in dichloromethane, oxidation at the benzyl position occurred, forming iminium ions. These intermediates were trapped by intramolecular reaction with the hydroxyls, and the resulting intermediates were then oxidized or shifted to afford 25 and 24, respectively. The entire one-pot process involves N-debenzylation, N-chlorination, and hemiacetal oxidation. The amine N-oxide-directed epoxidation complements Davies' ammonium-directed epoxidation. Thus, TCCA N-debenzylation is described for the first time and might be a useful N-debenzylation technique.
TL;DR: The fate of the aryl gold(I) carbenes generated by retro-Buchner reaction of ortho-substituted 7-aryl-1,3,5-cycloheptatrienes is dependent on the constitution of the ortho substituent as discussed by the authors.
Abstract: The fate of the aryl gold(I) carbenes generated by retro-Buchner reaction of ortho-substituted 7-aryl-1,3,5-cycloheptatrienes is dependent on the constitution of the ortho substituent. Indenes and fluorenes are obtained by intramolecular reaction of highly electrophilic gold(I) carbenes with alkenes and arenes. According to density functional theory calculations, the gold-catalyzed retro-Buchner process occurs stepwise, although the two carbon–carbon cleavages occur on a rather flat potential energy surface.
TL;DR: In this paper, in situ generated carbanions with dialkyl peroxides are demonstrated to proceed intramolecularly to yield cyclic ethers (II) and (IV).
Abstract: Reaction of in situ generated carbanions with dialkyl peroxides is demonstrated to proceed intramolecularly to yield cyclic ethers (II) and (IV).
TL;DR: In this article, it was shown that α-amino acid amide derivatives of 2-aminobenzothiazoles undergo a time-dependent, thermal rearrangement in which the amine group attacks the 2-position carbon of the thiazole ring to form a 5,5-spiro ring system.
Abstract: We have found that α-amino acid amide derivatives of 2-aminobenzothiazoles undergo a time-dependent, thermal rearrangement in which the amine group attacks the 2-position carbon of the thiazole ring to form a 5,5-spiro ring system. This is followed by sulfur leaving and air oxidation to the corresponding symmetrical disulfide. The isolated yields of such products are quite high (>70%) if there is conformational bias to further promote the intramolecular reaction such as for the 2-aminobenzothiazole amides derived from proline or 4-aminopiperidine-4-carboxylic acid. This rearrangement has not been described previously for α-amino acid amide derivatives of 2-aminobenzothiazoles. However, a related reaction involving 2-semicarbazido benzothiazoles has been recently reported.
TL;DR: In this paper, a new protocol was developed for the synthesis of 2,3-dihydroimidazo[1,2-c]pyrimidines, based on an intramolecular reaction between a pyrimidine nitrogen atom and an acetal moiety in the presence of boron trifluoride etherate.
Abstract: A new protocol was developed for the synthesis of 2,3-dihydroimidazo[1,2-c]pyrimidines, based on an intramolecular reaction between a pyrimidine nitrogen atom and an acetal moiety in the presence of boron trifluoride etherate. The method was expanded to permit the synthesis of the triheterocyclic imidazo[1,2-c]pyrazolo[4,3-e]pyrimidine system.
TL;DR: In this paper, an efficient gold-I-catalyzed alkenylation of β-alkyne-substituted pyrroles was reported, which gave straightforward access to different types of seven-membered-ring-fused pyrrole with endo-selectivity.
Abstract: An efficient gold(I)-catalyzed alkenylation of β-alkyne-substituted pyrroles is reported. The intramolecular reaction gives straightforward access to different types of seven-membered-ring-fused pyrroles with endo-selectivity, and the intermolecular reaction with alkynes provides functionalized pyrrole derivatives.
TL;DR: In this article, an α-nitro-δ-keto-nitrile readily forms the corresponding ammonium salt immediately upon treatment with an amine, when the amine liberated under equilibrium, the nucleophilic amine and the electrophilic keto nitrile come close to each other to afford so-called an intimate pair.
Abstract: An α-nitro-δ-keto nitrile readily forms the corresponding ammonium salt immediately upon treatment with an amine. When the amine liberated under equilibrium, the nucleophilic amine and the electrophilic keto nitrile come close to each other to afford so-called an intimate pair. The spatial proximity realized an efficient reaction to give a 2-amino-3-nitro-1,4-dihydropyridine; the reaction proceeded like an intramolecular reaction although it is actually an intermolecular reaction, namely the pseudo-intramolecular reaction. The bifunctionality of the keto nitrile also enabled the pseudo-intramolecular imination followed by tandem cyclization leading to diazabicyclic frameworks.