Showing papers on "Intramolecular reaction published in 2016"
TL;DR: Highly functionalized 4-bromo- 1,2-dihydroisoquinolines were synthesized from readily available 4-(2-(bromomethyl)phenyl)-1-sulfonyl-1,2,3-triazoles and a bromonium ylide is proposed as the key intermediate.
Abstract: Highly functionalized 4-bromo-1,2-dihydroisoquinolines were synthesized from readily available 4-(2-(bromomethyl)phenyl)-1-sulfonyl-1,2,3-triazoles. A bromonium ylide is proposed as the key intermediate, which can be formed by the intramolecular nucleophilic attack of the benzyl bromide on the α-imino rhodium carbene formed in the presence of the rhodium catalyst.
88 citations
TL;DR: Designer substrates, which under simple and practical reaction conditions generate a variety of cyclopenta[b]annulated arenes and heteroarenes in excellent enantiopurities and near-quantitative yields in remarkably short reaction times, are described.
Abstract: The first enantioselective organocatalytic intramolecular Morita-Baylis-Hillman (MBH) reaction of sterically highly demanding β,β-disubstituted enones is presented. The MBH reaction of β,β-disubstituted-α,β-unsaturated electron-withdrawing systems was previously considered to be unfeasible. Towards this end, designer substrates, which under simple and practical reaction conditions generate a variety of cyclopenta[b]annulated arenes and heteroarenes in excellent enantiopurities and near-quantitative yields in remarkably short reaction times, are described. The reason for the unusually facile nature of this reaction is attributed to the synergy guided and entropically favored intramolecular reaction. Further, this strategy provides easy access to a substantial number of bioactive natural products and pharmaceutically significant compounds.
57 citations
TL;DR: The Rh(II) -catalyzed oxyamination and diamination of alkenes generate 1, 2-amino alcohols and 1,2-diamines, respectively, in good to excellent yields and with complete regiocontrol.
Abstract: The Rh(II) -catalyzed oxyamination and diamination of alkenes generate 1,2-amino alcohols and 1,2-diamines, respectively, in good to excellent yields and with complete regiocontrol. In the case of diamination, the intramolecular reaction provides an efficient method for the preparation of pyrrolidines, and the intermolecular reaction produces vicinal amines with orthogonal protecting groups. These alkene difunctionalizations proceed by aziridination followed by nucleophilic ring opening induced by an Rh-bound nitrene generated in situ, details of which were uncovered by both experimental and theoretical studies. In particular, DFT calculations show that the nitrogen atom of the putative [Rh]2 =NR metallanitrene intermediate is electrophilic and support an aziridine activation pathway by N⋅⋅⋅N=[Rh]2 bond formation, in addition to the N⋅⋅⋅[Rh]2 =NR coordination mode.
51 citations
TL;DR: The intramolecular reaction gave planar-chiral naphthalene- and anthracene-fused ferrocene derivatives with high to excellent ee.
Abstract: Enantioselective cycloisomerization of 2-ethynyl-1-ferrocenylbenzene derivatives proceeded by using a chiral cationic platinum catalyst at room temperature. The intramolecular reaction gave planar-chiral naphthalene- and anthracene-fused ferrocene derivatives with high to excellent ee.
42 citations
TL;DR: It is demonstrated that a simple cobalt complex can regioselectively couple epoxides and aziridines with alkenes to generate valuable homoallylic alcohols and amines, in contrast to traditional Mizoroki-Heck reactions.
35 citations
TL;DR: A convenient approach for the synthesis of 1,4-diketones bearing an amino group has been developed through the K2CO3-catalyzed reaction of 2-oxindoles with enones with the assistance of atmospheric O2 via sequential Michael addition-oxidation-ring-cleavage process.
Abstract: A convenient approach for the synthesis of 1,4-diketones bearing an amino group has been developed through the K2CO3-catalyzed reaction of 2-oxindoles with enones with the assistance of atmospheric O2 via sequential Michael addition–oxidation–ring-cleavage process. The further intramolecular reaction leads to the formation of benzoazepinone, quinoline, and 3-oxindole derivatives.
23 citations
TL;DR: In this article, a mononuclear thiolato nickel complex, (PPP)Ni(SAr) (1a,b) was prepared by treating the chloride starting material with NaSPh.
16 citations
TL;DR: The gold(I)-catalyzed intramolecular reaction of allenes with oxoalkenes leads to bicyclo[6.3.0]undecane ring systems, although in the case of terminally disubstituted allenes, seven-membered rings are formed.
15 citations
TL;DR: Selective gold(I)-catalyzed rearrangement of aromatic methoxypropynyl acetals leads to fused catechol ethers (1,2-dialkoxynapthalenes) in excellent yields and this process extends to the analogous heterocyclic and aliphatic substrates.
12 citations
TL;DR: A novel and efficient synthesis of isatins from α-hydroxy amides via ruthenium-mediated aromatic C-H activation is described, which opens up an interesting and attractive avenue for the application of intramolecular ortho-C–H activation.
11 citations
TL;DR: An efficient one-pot intermolecular reductive cross-coupling of unactivated primary and secondary alkyl chlorides bearing β-hydrogens with aryl bromides is described, and the conditions were also successfully extended to an intramolecular reaction for the first time.
Abstract: An efficient one-pot intermolecular reductive cross-coupling of unactivated primary and secondary alkyl chlorides bearing β-hydrogens with aryl bromides is described. A combination of magnesium turnings and a catalytic amount of the commercially available iron(III) complex Fe(PPh3)2Cl3 was used, and the conditions were also successfully extended to an intramolecular reaction for the first time. Both types of cross-coupling reactions proceed under mild conditions, involving the in situ generation of aryl Grignard reagents, and show good applicability to a variety of readily available unactivated alkyl chlorides, which have previously been challenging substrates in iron-catalyzed reductive cross-coupling reactions.
TL;DR: In this paper, the preparation of new thiadiazoles through a simple intramolecular reaction of mono-and bis-hydrazonoyl halides with methyl hydrogen phenyl carbonimidodithioate or methyl-2-arylidene hy-drazine carbodithiotate was described.
Abstract: The present work describes the preparation of new thiadiazoles through a simple intramolecular reaction of mono- and bis-hydrazonoyl halides with methyl hydrogen phenyl carbonimidodithioate or methyl-2-arylidene hy- drazinecarbodithioate. The synthetic method involves nucleophilic substitution followed by intramolecular cyclization reactions mediated by evolution of methanethiol. The structures of the title compounds were elucidated by elemental analyses, and FTIR, MS and NMR spectra.
TL;DR: In this paper, the second-order rate constants for deuteroxide-catalysed exchange in aqueous solution of the C(2)-hydrogens of bis-propyl bis-imidazolium di-iodide salt 4 and related monomeric dipropyl imidisolium iodide 10 of kDO=1.37×104 and 1.79×102M-1s-1, respectively, were calculated.
TL;DR: In this paper, a bromonium ylide is proposed as the key intermediate, which can be formed by the intramolecular nucleophilic attack of the benzyl bromide on the α-imino rhodium carbene formed in the presence of the catalytic catalyst.
Abstract: Highly functionalized 4-bromo-1,2-dihydroisoquinolines were synthesized from readily available 4-(2-(bromomethyl)phenyl)-1-sulfonyl-1,2,3-triazoles. A bromonium ylide is proposed as the key intermediate, which can be formed by the intramolecular nucleophilic attack of the benzyl bromide on the α-imino rhodium carbene formed in the presence of the rhodium catalyst.
TL;DR: An efficient synthesis of dihydrobenzo[c]phenanthridinones was achieved by utilizing an indium(0)-mediated intramolecular cyclization reaction under ligand- and base-free conditions.
Abstract: An efficient synthesis of dihydrobenzo[c]phenanthridinones was achieved by utilizing an indium(0)-mediated intramolecular cyclization reaction under ligand- and base-free conditions. A variety of functional groups were tolerated in the present protocol.
TL;DR: In this article, cyclocondensation of 1-hydroxyketones with thiosemicarbazide resulted in thiadiazines, and bromoacetyl-substituted nitrate ester of 1hydroxy ketone, condensation proceeded via intramolecular reaction between the thiol and Bromomethyl groups.
Abstract: Cyclocondensation of 1-hydroxyketones with thiosemicarbazide resulted in thiadiazines. Nitrate ester of 1-hydroxyketone reacted under similar conditions to give the corresponding thiosemicarbazone. In the case of bromoacetyl-substituted nitrate ester of 1-hydroxyketone, condensation proceeded via intramolecular reaction between the thiol and bromomethyl groups.
TL;DR: In this paper, reactionpathway control of 2-lithio-2′-silylbiphenyls was accomplished in flow microreactor systems by choosing an appropriate residence time and temperature region.
Abstract: Reaction-pathway control of 2-lithio-2′-silylbiphenyls was accomplished in flow microreactor systems. Effective switching between the intermolecular reaction with an electrophile and the intramolecular reaction was performed at will by choosing an appropriate residence time and temperature region.
TL;DR: The first enantioselective organocatalytic intramolecular Morita-Baylis-Hillman (MBH) reaction of sterically highly demanding β,β-disubstituted enones is presented in this paper.
Abstract: The first enantioselective organocatalytic intramolecular Morita-Baylis-Hillman (MBH) reaction of sterically highly demanding β,β-disubstituted enones is presented. The MBH reaction of β,β-disubstituted-α,β-unsaturated electron-withdrawing systems was previously considered to be unfeasible. Towards this end, designer substrates, which under simple and practical reaction conditions generate a variety of cyclopenta[b]annulated arenes and heteroarenes in excellent enantiopurities and near-quantitative yields in remarkably short reaction times, are described. The reason for the unusually facile nature of this reaction is attributed to the synergy guided and entropically favored intramolecular reaction. Further, this strategy provides easy access to a substantial number of bioactive natural products and pharmaceutically significant compounds.
TL;DR: In this paper, an efficient synthesis of dihydrobenzo[c]phenanthridinones was achieved by utilizing an indium(0)-mediated intramolecular cyclization reaction under ligand and base-free conditions.
Abstract: An efficient synthesis of dihydrobenzo[c]phenanthridinones was achieved by utilizing an indium(0)-mediated intramolecular cyclization reaction under ligand- and base-free conditions. A variety of functional groups were tolerated in the present protocol.
TL;DR: In this paper, the substituent effect of the pentafluorophenyl (PhF 5 ) groups on the Ru-porphyrin complex-catalyzed intramolecular reaction was investigated with density function theory calculations.
16 Sep 2016
TL;DR: In this paper, a series of fused dihydrodibenzobarrelene (dibenzobicyclo[2.2]octadiene) and lactone rings were prepared via a one-pot synthesis in which a Diels-Alder reaction occurred followed by an intramolecular transesterification to form the lactone ring.
Abstract: A series of fused dihydrodibenzobarrelene (dibenzobicyclo[2.2.2]octadiene) and lactone rings were prepared from dialkyl fumarates and 9-anthracenemethanol. These products were prepared via a one-pot synthesis in which a Diels-Alder reaction occurred followed by an intramolecular transesterification to form the lactone ring. A key feature of this synthetic methodology is the straightforward purification of the reaction products, in most cases without the need for chromatography. The ease of work-up along with the simple setup of the reaction (no catalysts or other reagents needed) make this methodology a convenient and potentially scalable route to complex, multicyclic structures. Molecular modeling of the transition structures for Diels-Alder reaction suggested that transesterification could precede cycloaddition, but NMR in situ studies confirmed the opposite occurrence. Product formed exclusively in the trans configuration for all alkyl fumarates used.
01 Jan 2016
TL;DR: The sol to gel transition in inorganic systems is a process which is highly dependent on the synthesis conditions; the chemistry of silicon alkoxides, in particular, is very difficult to handle because so many different species can form from the very beginning of the process and a small change of the synthesis parameters is immediately reflected on the hydrolysis and condensation stages as mentioned in this paper.
Abstract: The sol to gel transition in inorganic systems is a process which is highly dependent on the synthesis conditions; the chemistry of silicon alkoxides , in particular, is very difficult to handle because so many different species can form from the very beginning of the process and a small change of the synthesis parameters is immediately reflected on the hydrolysis and condensation stages.
TL;DR: An efficient one-pot intermolecular reductive cross-coupling of unactivated primary and secondary alkyl chlorides bearing β-hydrogens with aryl bromides is described in this article.
Abstract: An efficient one-pot intermolecular reductive cross-coupling of unactivated primary and secondary alkyl chlorides bearing β-hydrogens with aryl bromides is described. A combination of magnesium turnings and a catalytic amount of the commercially available iron(III) complex Fe(PPh3)2Cl3 was used, and the conditions were also successfully extended to an intramolecular reaction for the first time. Both types of cross-coupling reactions proceed under mild conditions, involving the in situ generation of aryl Grignard reagents, and show good applicability to a variety of readily available unactivated alkyl chlorides, which have previously been challenging substrates in iron-catalyzed reductive cross-coupling reactions.
TL;DR: The gold-catalyzed intramolecular reaction of allenes with oxoalkenes leads to bicyclo[6.3]undecane ring systems, although in the case of terminally disubstituted allenes, seven-membered rings are formed as discussed by the authors.
Abstract: The gold(I)-catalyzed intramolecular reaction of allenes with oxoalkenes leads to bicyclo[6.3.0]undecane ring systems, although in the case of terminally disubstituted allenes, seven-membered rings are formed. The related intermolecular addition of aldehydes to allenenes also gives seven-membered rings.
DOI•
01 Jul 2016TL;DR: In this article, the authors presented a novel approach in the intramolecular redox reactions in the solid state, and provided insight into the synthesis of metal nanoparticles via metal hydrazine complexes at room temperature.
Abstract: Ni6(N2H4)6(SO4)4(OH)2(H2O)8](SO4)(H2O)10 complex was prepared according to literature report. The reaction between aforementioned complex via sodium alkoxides as a reactants, were carried out in the solid state. The [Ni6(N2H4)6(SO4)4(OH)2(H2O)8](SO4)(H2O)10 undergoes an intramolecular two electrons oxidation-reduction reaction at room temperature and metallic nickel nanoparticles (Ni1-Ni5) was produced. The aforesaid complex contains nickel (II) as an oxidizing agent and also hydrazine ligand as a reducing agent. Its redox reaction leads to the formation of other products, sodium azide and ammonia gas and alcohols. In such a solid state reaction, not only the intramolecular redox reaction is important but also it is a novel method in the synthesis of nanoparticles. The nickel metal nanoparticles were characterized using X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) analysis. The synthesized nickel nanoparticles have similar morphologies however the particle size distributions are different. The nickel nanoparticles have particle size distributions ranging from 10 to 75 nm. This work presents a novel approach in the intramolecular redox reactions in the solid state, and provides insight into the synthesis of metal nanoparticles via metal hydrazine complexes at room temperature.
TL;DR: In this paper, a diastereoselective C-H and C-C bond formation has been assessed from rubrene to form selectively one indenonaphthacene derivative R*, in the presence of metallic potassium stabilised by THF at room temperature.
Abstract: Diastereoselective C–H and C–C bond formation has been assessed from rubrene to form selectively one indenonaphthacene derivative R*, in the presence of metallic potassium stabilised by THF at room temperature. The potassium salt [K(rac-R*)(THF)x] contains R* as anion with a (1S,2S) and (1R,2R) configuration, on the two new chiral carbon centers, which has been unambiguously confirmed by selective 1D NOESY, 1H, 13C-NMR, 1H, 13C-HMBC and polarimetry. The stated chirality could only originate from a face selective intramolecular reaction, which takes place on one side of the original tetracene core. The diastereomeric excess for the potassium salt has been quantified by 1H NMR to be at least 97%. Potassium removal affords the neutral ((S,S)+(R,R))-R*. In contrast, the acid-based protocol furnishes two structural isomers, ((S,R)+(R,S))-R* and rac-R′. The former compound has been isolated pure with a yield of 56% by precipitation. The complementary chirality in R* is a direct consequence of the inter- and intramolecular character for both face-selective processes, along with potassium assistance in the latter case.
TL;DR: In this article, a gold-catalyzed rearrangement of aromatic methoxypropynyl acetals leads to fused catechol ethers (1,2-dialkoxynapthalenes) in excellent yields.
Abstract: Selective gold(I)-catalyzed rearrangement of aromatic methoxypropynyl acetals leads to fused catechol ethers (1,2-dialkoxynapthalenes) in excellent yields. Furthermore, this process extends to the analogous heterocyclic and aliphatic substrates. Alkyne activation triggers nucleophilic addition of the acetal oxygen that leads to an equilibrating mixture of oxonium ions of similar stability. This mixture is “kinetically self-sorted” via a highly exothermic cyclization. Selective formation of 1,2-dialkoxy naphthalenes originates from chemoselective aromatization of the cyclic intermediate via 1,4-elimination of methanol.
TL;DR: Peczuh et al. as mentioned in this paper compared the rearrangement of a small molecule to the process of turning a stuffed animal inside out, and found that the epoxidation of some highly functionalized spiroketal compounds promoted rearrangements of their structures that turned them inside out.
Abstract: Invited for this month's cover picture is the group of Professor Mark Peczuh at the University of Connecticut. The cover picture compares the rearrangement of a small molecule to the process of turning a stuffed animal inside out. The recycled, inside-out stuffed animals are both artistic and philosophically provocative. They capture the essence of the rearrangement reaction because the compounds themselves turn inside out over the course of the reaction, extending the diversity of products that can arise from simple starting materials. Small molecules often have functional groups with latent reactivity; under the appropriate conditions, those groups can react with other compounds (e.g., reagents) and also with other groups in the same molecule in an intramolecular reaction. The research team found that the epoxidation of some highly functionalized spiroketal compounds promoted rearrangements of their structures that turned them inside out. Some of the features of the products led them to use X-ray crystallography or a combination of computer-assisted structure elucidation, computation, and a new version of the 1,1-ADEQUATE NMR experiment to determine their structures. For more details, see the Communication on p. 577 ff.
01 May 2016
TL;DR: In this article, a novel Hg2+ ion induced reversible ring contraction was achieved employing the intramolecular reaction of isobutylene with an aromatic hydroxyl group of cyclophane; reversibility of the reaction was facilitated by excess addition of NaBH4 which also resulted in complexation.
Abstract: A novel Hg2+ ion induced reversible ring contraction was achieved employing the intramolecular reaction of isobutylene with an aromatic hydroxyl group of cyclophane; reversibility of the reaction was facilitated by excess addition of NaBH4 which also resulted in complexation. The ring contraction and expansion was monitored by UV-VIS absorption, and by fluorescence and 1H NMR spectra. Switchable fluorescence behavior (on—off—on) was observed when the ring-size was tuned from a 19-membered ring to an 18-membered and vice versa. This fine tuning has the potential to be applied in the construction of new supramolecular devices.
TL;DR: In this article, a convenient approach for the synthesis of 1,4-diketones bearing an amino group has been developed through the K2CO3-catalyzed reaction of 2-oxindoles with enones with the assistance of atmospheric O2 via sequential Michael addition-oxidation-ring-cleavage process.
Abstract: A convenient approach for the synthesis of 1,4-diketones bearing an amino group has been developed through the K2CO3-catalyzed reaction of 2-oxindoles with enones with the assistance of atmospheric O2 via sequential Michael addition–oxidation–ring-cleavage process. The further intramolecular reaction leads to the formation of benzoazepinone, quinoline, and 3-oxindole derivatives.