Showing papers on "Intramolecular reaction published in 2010"
TL;DR: The intramolecular reaction of donor-acceptor cyclopropanes with various dipoles and dipolar equivalents allows access to a variety of bicyclic adducts with good stereo control as discussed by the authors.
Abstract: The intramolecular reaction of donor-acceptor cyclopropanes with various dipoles and dipolar equivalents allows access to a variety of bicyclic adducts with good stereo control The linkers can often be cleaved to provide stereodefined products
144 citations
TL;DR: In this paper, the reaction mechanism of primary aliphatic amines with CO2 was investigated, and the final product was formed by the intramolecular dehydration, which was obtained at the optimized conditions that are comparable to the presence of catalyst and solvent.
139 citations
TL;DR: A new and efficient strategy for the synthesis of substituted quinolines via electrophilic cyclization is developed, and the intramolecular cyclization of 1-azido-2-(2-propynyl)benzene 1 proceeds smoothly in the presence of electrophobic reagents.
Abstract: A new and efficient strategy for the synthesis of substituted quinolines via electrophilic cyclization is developed. The intramolecular cyclization of 1-azido-2-(2-propynyl)benzene 1 proceeds smoothly in the presence of electrophilic reagents (I2, Br2, ICl, NBS, NIS, and HNTf2) in CH3NO2 at room temperature or in the presence of catalytic amounts of AuCl3/AgNTf2 in THF at 100 °C to afford the corresponding quinolines 2 in good to high yields. In the case of the electrophilic reagents, E of 2 is either I, Br, or H, depending on the reagent type, while E of 2 is H in the case of the electrophilic catalyst.
126 citations
TL;DR: In this paper, a solid-phase assembly of model peptides derived from human parathyroid hormone-related protein (11−19) containing ω-azido- and ωyl-α-amino acid residues in positions i and i+4 was cyclised in solution by an intramolecular CuI-catalyzed azide-alkyne 1,3-dipolar Huisgen cycloaddition.
97 citations
TL;DR: The synthesis of 3H-indoles was achieved via the iodine-mediated intramolecular cyclization of enamine derivatives bearing multifunctional groups in good to high yields under transition metal-free reaction conditions.
Abstract: The synthesis of 3H-indoles was achieved via the iodine-mediated intramolecular cyclization of enamines. A wide variety of 3H-indole derivatives bearing multifunctional groups were obtained in good to high yields under transition metal-free reaction conditions.
92 citations
TL;DR: A general synthesis of 3-chalcogen benzo[b]furans from the readily available 2-alkynylanisoles, via FeCl(3)/diorganyl dichalcogenides intramolecular cyclization, has been developed and it is revealed that the reaction significantly depends on the electronic effects of substituents in the aromatic ring bonded to the selenium atom of the diselenide species.
Abstract: A general synthesis of 3-chalcogen benzo[b]furans from the readily available 2-alkynylanisoles, via FeCl3/diorganyl dichalcogenides intramolecular cyclization, has been developed. Aryl and alkyl groups directly bonded to the chalcogen atom were used as cycling agents. The results revealed that the reaction significantly depends on the electronic effects of substituents in the aromatic ring bonded to the selenium atom of the diselenide species. We observed that the pathway of reaction was not sensitive to the nature of substituents in the aromatic ring of anisole since both the electron-donating and the electron-withdrawing groups delivered the products in similar yields. In addition, the obtained heterocycles were readily transformed to more complex products by using a chalcogen/lithium exchange reaction with n-BuLi followed by trapping of the lithium intermediate with aldehydes, furnishing the desired secondary alcohols in good yields.
85 citations
81 citations
TL;DR: It was found that three types of reactions may coexist in Cu-mediated reactions between iododifluoroacetamides and aryl/alkenyl iodides: cross-coupling, intramolecular cyclization, and homocoupling reactions.
Abstract: Cu-mediated fluoroalkylation reactions with iododifluoroacetamides 1 have been systematically investigated. It was found that three types of reactions may coexist in Cu-mediated reactions between iododifluoroacetamides and aryl/alkenyl iodides: cross-coupling, intramolecular cyclization, and homocoupling reactions. The selectivity among these three types of reactions could be controlled by tuning the substituents on the nitrogen atom of iododifluoroacetamides, and/or by removing the cross-coupling reaction partner (aryl/alkenyl halides). The general rule is as follows: (a) in the presence of proper aryl/alkenyl iodides, the cross-coupling products 2 (or 6) are generally formed as the major products; (b) in the absence of aryl/alkenyl iodides, and when R(1) = alkyl and R(2) = aryl groups, or when R(1) = R(2) = aryl groups, the intramolecular cyclization products 3 can be formed predominantly; and (c) in the absence of aryl/alkenyl iodides, and when R(1) = R(2) = alkyl groups, or when R(1) = H and R(2) = alkyl, aryl groups, the homocoupling products 4 can be formed dominantly. Our experimental results also indicate that in many cases when cross-coupling, homocoupling, and intramolecular cyclization reactions coexist in the Cu-mediated reaction system, the reactivity decreases in the following order: cross-coupling > intramolecular cyclization > homocoupling.
80 citations
TL;DR: The Fe(ClO(4))(3)-catalyzed intramolecular rearrangement/cyclization/oxidation reaction sequence for the synthesis of alpha-carbonyl furan derivatives from electron-deficient alkynes and 2-yn-1-ols is reported.
Abstract: The Fe(ClO4)3-catalyzed intramolecular rearrangement/cyclization/oxidation reaction sequence for the synthesis of α-carbonyl furan derivatives from electron-deficient alkynes and 2-yn-1-ols is reported.
77 citations
TL;DR: The synthesis of a series of substituted phenanthridines by photostimulated C-C cyclization of anions from N-(ortho-halobenzyl)arylamines has been found to proceed in very good to excellent yields in liquid ammonia and in DMSO.
Abstract: The synthesis of a series of substituted phenanthridines by photostimulated C-C cyclization of anions from N-(ortho-halobenzyl)arylamines has been found to proceed in very good to excellent yields (79-95%) in liquid ammonia and in DMSO. The N-(ortho-halobenzyl)arylamines are obtained in good to very good isolated yields (44-85%) by nucleophilic substitution of ortho-halobenzylchlorides with different arylamines. The reaction of the anions of a diverse set of N-(ortho-halobenzyl)arylamines was studied, and the methodology was extended to the synthesis of trispheridine, a natural product, in very good yield. In order to explain the regiochemical outcome of these reactions, a theoretical analysis was performed with DFT methods and the B3LYP functional.
69 citations
TL;DR: In this article, a thorough and detailed computational analysis was performed on the hydride- and halide-induced ring openings of 1-benzyl-1-(α-(R)-methylbenzinzyl)-2(S)-(phenoxymethyl)aziridinium bromide.
Abstract: The ring opening of 2-substituted N,N-dibenzylaziridinium ions by bromide is known to occur exclusively at the substituted aziridine carbon atom via an SN2 mechanism, whereas the opposite regioselectivity has been observed as the main pathway for ring opening by fluoride. Similarly, the hydride-induced ring opening of 2-substituted N,N-dibenzylaziridinium ions has been shown to take place solely at the less hindered position. To gain insight into the main factors causing this difference in regioselectivity, a thorough and detailed computational analysis was performed on the hydride- and halide-induced ring openings of 1-benzyl-1-(α-(R)-methylbenzyl)-2(S)-(phenoxymethyl)aziridinium bromide. Intramolecular π−π stacking interactions in the aziridinium system were investigated at a range of levels that enable a proper description of dispersive interactions; a T-stacking conformer was found to be the most stable. Ring-opening mechanisms were investigated with a variety of DFT and high level ab initio methods t...
TL;DR: The use of Pd(II)/bis-sulfoxide 1 catalyzed intra- and intermolecular allylic C-H amination reactions to rapidly diversify structures containing a sensitive β-lactam core similar to that found in the monobactam antibiotic Aztreonam is described.
TL;DR: A variety of 3-vinyl-substituted imidazo[1,5-a]indole derivatives were synthesized by intramolecular Pd-catalyzed cyclization of the title allenamides through either a domino carbopalladation/exo-cyclization process or a novel hydroamination reaction that proceeds smoothly under microwave irradiation.
Abstract: A variety of 3-vinyl-substituted imidazo[1,5-a]indole derivatives were synthesized by intramolecular Pd-catalyzed cyclization of the title allenamides through either a domino carbopalladation/exo-cyclization process or a novel hydroamination reaction that proceeds smoothly under microwave irradiation. Both the observed pathways involve a π-allyl-palladium(II) complex arising from insertion of the allene group into a palladium(II) species, the latter being formed in situ by the intervention of an aryl iodide or of the N−H group. In both cases, the role of nucleophile is covered by the indole nitrogen.
TL;DR: This method is also applicable to the preparation of 2,3-dihydro-4H-pyran-4-ones and the substituted 3(2H)-furanones in 55-94% yields.
Abstract: The combination of (p-CF3C6H4)3PAuCl and AgOTf generates a powerful catalyst for the intramolecular cyclizations of readily available γ-hydroxyalkynones under mild conditions. The substituted 3(2H)-furanones are obtained in 55−94% yields. This method is also applicable to the preparation of 2,3-dihydro-4H-pyran-4-ones.
TL;DR: In this paper, a brief review represents the synthesis of heterocyclic compounds via application of Heck reaction in recent years, showing that the Heck reaction can be used to synthesize a variety of compounds.
Abstract: This brief review represents the synthesis of heterocyclic compounds via application of Heck reaction in recent years.
TL;DR: Treatment of a wide range of functionalized hydroxyallenic esters with 5 mol % Ph(3)PAuCl and AgOTf in CH(2)Cl(2), producing selectively 2-alkyl- and aryl-3-ethoxycarbonyl-2,5-dihydrofurans in good to excellent yield through intramolecular hydroalkoxylation by a 5-endo mode.
Abstract: Treatment of a wide range of functionalized hydroxyallenic esters with 5 mol % Ph3PAuCl and 5 mol % AgOTf in CH2Cl2 at 25 °C for 1 h produced selectively 2-alkyl- and aryl-3-ethoxycarbonyl-2,5-dihydrofurans in good to excellent yield through intramolecular hydroalkoxylation by a 5-endo mode.
TL;DR: The enantioselective cyanoamidation was accomplished with Pd(dba)2 and an opticallyactive phosphoramidite to provide optically active 3,3-disubstituted oxindoles and Manipulation of the resulting oxindole has been studied.
TL;DR: These NIS-mediated alkoxyamination and diamination protocols were effective for a range of N-δ-alkenyl-N'-sulfonyl ureas to form the corresponding heterobicyclic compounds in good yield with high chemoselectivities and good to excellent diastereoselectivity.
TL;DR: ABC analogues of the antitumor antibiotic lavendamycin were prepared via the palladium(0)-catalyzed cross-coupling reaction of various 2-haloheteroaromatics with 2-stannylated pyridines and quinolines using the Stille reaction, which efficiently provided several new heterobiaryl derivatives.
Abstract: ABC analogues of the antitumor antibiotic lavendamycin, which contain the key metal chelation site and redox-active quinone unit essential for biological activity, were prepared via the palladium(0)-catalyzed cross-coupling reaction of various 2-haloheteroaromatics with 2-stannylated pyridines and quinolines. Using the Stille reaction, 2-bromo substituted quinolines and 1-bromoisoquinolines were found to undergo efficient coupling with 2-pyridinylstannanes to provide unsymmetrical heterobiaryl derivatives. While the Stille reaction using the reverse coupling partners (i.e., 2-quinolinylstannanes and haloheteroaromatics) had not received much attention in the literature, we found that this alternative coupling reaction efficiently provided several new heterobiaryl derivatives. The gold-catalyzed intramolecular cycloisomerization of N-(prop-2-ynyl)-1H-indole-2-carboxamide smoothly afforded a β-carbolinone derivative that was subsequently used for a Pd(0)-catalyzed cross-coupling directed toward the synthesi...
TL;DR: An efficient acid-catalyzed approach to the synthesis of functional 1,4-dihydropyridines from the reaction of readily available enaminones with aldehydes has been developed by a cascade reaction involving first formation of divinylmethanes and subsequent intramolecular cyclization.
TL;DR: Synthesis of a C(15)-desmethyl tricycle core of lycopodine has been accomplished and N-(p-dodecylphenylsulfonyl)-2-pyrrolidinecarboxamide, an organocatalyst which facilitates enantioselective, intramolecular Michael additions, is described.
Abstract: Synthesis of a C(15)-desmethyl tricycle core of lycopodine has been accomplished. Key steps in the synthetic sequence include organocatalytic, intramolecular Michael addition of a keto sulfone and a tandem 1,3-sulfonyl shift/Mannich cyclization to construct the tricyclic core ring system. Synthetic work toward this natural product family led to the development of N-(p-dodecylphenylsulfonyl)-2-pyrrolidinecarboxamide, an organocatalyst which facilitates enantioselective, intramolecular Michael additions. A detailed mechanistic discussion is provided for both the intramolecular Michael addition and the sulfone rearrangement. Finally, the application of these discoveries to the enantioselective total synthesis of alkaloid lycopodine is described.
TL;DR: Two new kinds of tetrahydrobenzo[b]imidazo[3,2,1-ij][1,8]naphthyridine derivatives have been successfully synthesized by cascade reactions by simply incorporating an o-halo group into the aryl ring of 2-benzoylmethyleneimidazolidine as new synthons.
Abstract: Two new kinds of tetrahydrobenzo[b]imidazo[3,2,1-ij][1,8]naphthyridine derivatives have been successfully synthesized by cascade reactions including Knoevenagel condensation, aza-ene reaction, imine−enamine tautomerization, cyclocondensation, and intramolecular SNAr of precursors 2-(2-chloroaroyl)methyleneimidazolidines with aromatic aldehydes and ethyl acetoacetate or Meldrum’s acid under mild conditions, respectively. These studies highlighted the concept of a substrate-design approach to the development of novel multicomponent reactions by simply incorporating an o-halo group into the aryl ring of 2-benzoylmethyleneimidazolidine as new synthons. In this domino reaction, at least six different active sites are involved; two C−C bonds, two C−N bonds, and two new rings are constructed with all reactants efficiently utilized in the chemical transformation.
TL;DR: Intramolecular C-H arylations were employed as a key step in the synthesis of hitherto unknown fused purine systems: 13-substituted purino[8,9-f]phenanthridines and 11-subStituted 5,6-dihydropurino[7,8-a]isoquinolines.
Abstract: Intramolecular C−H arylations were employed as a key step in the synthesis of hitherto unknown fused purine systems: 13-substituted purino[8,9-f]phenanthridines and 11-substituted 5,6-dihydropurino[8,9-a]isoquinolines. The purino[8,9-f]phenanthridines were prepared in moderate yields by double C−H arylations of 9-phenylpurines with 1,2-diiodobenzene or, more efficiently, by consecutive Suzuki coupling of 9-(2-bromophenyl)purines with 2-bromophenylboronic acid followed by intramolecular C−H arylation. 5,6-Dihydropurino[8,9-a]isoquinolines were prepared in quantitative yields by intramolecular C−H arylations of 9-(2-chlorophenethyl)purines.
TL;DR: The reaction mechanisms of the PtCl 4- and Au(I)-catalyzed intramolecular acetylenic Schmidt reactions were analyzed by means of hybrid density functional calculations at the B3LYP/6-31G*(LANL2DZ) level of theory for better understanding of the acceleration effect of ethanol solvent in PtCl4- catalyzed reaction and the different catalytic activities of Au and Pt catalysts.
Abstract: The reaction mechanisms of the PtCl4- and Au(I)-catalyzed intramolecular acetylenic Schmidt reactions were analyzed by means of hybrid density functional calculations at the B3LYP/6-31G*(LANL2DZ) level of theory for better understanding of the acceleration effect of ethanol solvent in PtCl4-catalyzed reaction and the different catalytic activities of Au and Pt catalysts. Calculations indicate the rate of the PtCl4-catalyzed reaction in noncoordinative solvent of 1,2-dichloroethane is limited by isomerization of the relatively stable chelate complex to the reactive π-complex of PtCl4 with the acetylenic moiety of homopropargyl azide substrate, which requires an activation energy of 29.6 kcal/mol. All nucleophilic cyclization, dinitrogen elimination, and 1,2-H shift of metal-carbene steps are quite facile. The generation of 2H-pyrrole intermediate in PtCl4-catalyzed reaction is completed by a ligand substitution reaction, and the final 2H-pyrrole to 1H-pyrrole isomerization is an intermolecular process with...
TL;DR: In the presence of ( R )-SEGPHOS-Pd(OAc) 2 catalyst, the intramolecular Narylation of ortho- tert -butyl-NH-anilides possessing an iodophenyl group proceeded in a highly enantioselective manner (89-98% ee) to give optically active atropisomeric lactams having an N-C chiral axis as discussed by the authors.
TL;DR: Macrocyclic polystrene (PSt) was produced in high yields by an intramolecular atom transfer radical coupling reaction of the chain ends as discussed by the authors. But the slow addition of the dibrominated polystyrene (BrPStBr)...
Abstract: Macrocyclic polystrene (PSt) was produced in high yields by an intramolecular atom transfer radical coupling reaction of the chain ends. The slow addition of the dibrominated polystyrene (BrPStBr) ...
TL;DR: In this paper, a wide range of 2-arylbenzo[ b ]furans are synthesized through domino intermolecular C (aryl) -C (alkynyl) bond formation followed by intramolecular O bond forming cyclization via copper(II)-catalyzed coupling of o -iodophenols and aryl terminal acetylenes.
TL;DR: Iminoisocoumarins and alpha-iminopyrones are prepared via Sonogashira coupling and AgOTf-catalyzed 6-endo-dig O-cyclization of the enyne-amide system in dichloroethane, in one pot or stepwise, respectively.
Abstract: Iminoisocoumarins and α-iminopyrones are prepared via Sonogashira coupling and AgOTf-catalyzed 6-endo-dig O-cyclization of the enyne−amide system in dichloroethane, in one pot or stepwise, respecti...
TL;DR: The enantioselective total syntheses of (+)-nankakurine A (2) and (+-nankkurine B (3) establish the relative and absolute configuration of these alkaloids and are sufficiently concise that substantial quantities of 2 and 3 were prepared for biological studies.
Abstract: The first total syntheses of the Lycopodium alkaloids (+)-nankakurine A (2), (+)-nankakurine B (3), and the originally purported structure 1 of nankakurine A were accomplished. The syntheses of 2 and 3 feature a demanding intramolecular azomethine imine cycloaddition as the key step for generating the octahydro-3,5-ethanoquinoline moiety and installing the correct relative configuration at the spiropiperidine ring juncture. The cyclization precursor was prepared from octahydronaphthalene ketone 50, which was assembled from enone (+)-9 and diene 48 by a cationic Diels−Alder reaction. The Diels−Alder reactants were synthesized from 5-hexyn-1-ol (16) and (+)-pulegone (49), respectively. The tetracyclic ring system of 1 was generated using an unprecedented nitrogen-terminated aza-Prins cyclization cascade. The enantioselective total syntheses of (+)-nankakurine A (2) and (+)-nankakurine B (3) establish the relative and absolute configuration of these alkaloids and are sufficiently concise that substantial qua...
TL;DR: This MCR followed by a postcondensation cyclization via an intramolecular S(N)Ar in the presence of K(2)CO(3) led to an unprecedented novel chromeno[2,3-b]quinoline framework containing an important chromene moiety in good yields.
Abstract: Regioselective synthesis of functionalized tetrahydrobenzo[b]pyrans has been developed by multicomponent reactions (MCRs) and tandem [3 + 3] annulations of β-benzoylthioacetanilides or β-(2-haloaroyl)thioacetanilides as valuable sources with aromatic aldehydes and 5,5-dimethyl-1,3-cyclohexanedione catalyzed by triethylamine. This MCR followed by a postcondensation cyclization via an intramolecular SNAr in the presence of K2CO3 led to an unprecedented novel chromeno[2,3-b]quinoline framework containing an important chromene moiety in good yields. The reactions were very mild, convenient, and o-selective to form new fused tetracyclic target molecules.