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1.
Quantum mechanical calculations show that N,N cycloaddition of alkenes and alkynes to s-tetrazines is possible as an alternative to the well-known C,C cycloaddition (Carboni-Lindsey reaction). Formation of 1,2,4-triazole derivatives (formal product of N,N cycloaddition) along with the pyrazole (formal product of C,C cycloaddition) corroborates this theoretical prediction. 相似文献
2.
Density functional theory (B3LYP) calculations on the transition states for the Huisgen 1,3-dipolar cycloadditions of phenyl azide with acetylene, cyclooctyne, and difluorocyclooctyne are reported. The low activation energy of the cyclooctyne "strain-promoted" cycloaddition (DeltaE = 8.0) compared to the strain-free acetylene cycloaddition (DeltaE = 16.2) is due to decreased distortion energy (DeltaEd) of cyclooctyne (DeltaDeltaEd = 4.6) and phenyl azide (DeltaDeltaEd = 4.5) to achieve that cycloaddition transition state. Electronegative fluorine substituents on cyclooctyne further increase the rate of cycloaddition by increasing interaction energies. 相似文献
3.
Wiggins KM Syrett JA Haddleton DM Bielawski CW 《Journal of the American Chemical Society》2011,133(18):7180-7189
Poly(methyl acrylate)s (PMAs) of varying molecular weights were grown from a [4+2] cycloaddition adduct of maleimide with furan containing two polymerization initiators. Subjecting the corresponding PMA (>30 kDa) chains to ultrasound at 0 °C resulted in a retro [4+2] cycloaddition reaction, as observed by gel permeation chromatography (GPC) and UV-vis spectroscopy, as well as labeling of the liberated maleimide and furan moieties with appropriate chromophores featuring complementary functional groups. Similar results were obtained by sonicating analogous polymers that were grown from a thermally robust [4+2] cycloaddition adduct of maleimide with anthracene. The generation of anthracenyl species from these latter adducts allowed for the rate of the corresponding mechanically activated retro [4+2] cycloaddition reaction to be measured. No reduction in the number average molecular weight (M(n)) or liberation of the maleimide, furan, or anthracene moieties was observed (i) for polymers containing the cycloaddition adducts with M(n) < 20 kDa, (ii) for high molecular weight PMAs (M(n) > 60 kDa) featuring terminal cycloaddition adducts, or (iii) when the cycloaddition adducts were not covalently linked to a high molecular weight PMA. Collectively, these results support the notion that the aforementioned retro [4+2] cycloaddition processes were derived from a vectorially opposed mechanical force applied to adducts embedded within the polymer chains. 相似文献
4.
Barry M. Trost Zhongxing Huang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(19):6462-6465
We describe the design and application of tailored aminoallyl precursors for catalytic (3+2) cycloaddition with conjugated dienes via a Pd‐aminoallyl intermediate. The new cycloaddition reactions override the conventional (4+3) selectivity of aminoallyl cation cycloaddition through a sequence of Pd‐allyl transfer and ring closure. A variety of highly substituted or fused pyrrolidine rings were synthesized using the cycloaddition, and can further undergo [1,3] N‐to‐C rearrangement to five‐membered carbocycles with a different palladium catalyst. The utility of the (3+2) cycloaddition is also demonstrated by the preparation of various derivatives from the bicyclic pyrrolidine products. 相似文献
5.
Li-li Shen Yong Ye Yong Luo Lun-zu Liu 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):680-687
1,3-Dipolar cycloaddition reactions are important synthetic manipulations allowing the construction of five-membered heterocycles. In this article, we report the cycloaddition of phosphonyl nitrile oxides with vinylphosphonate and phosphaalkyne to form the unexpected 2:1 cycloaddition product with excellent levels of regiocontrol product. The structures of title compounds were confirmed by 1H NMR, 31P NMR, MS, and IR. The mechanism of the cycloaddition was explored using the density functional theory (DFT) method. 相似文献
6.
Selby JD Schulten C Schwarz AD Stasch A Clot E Jones C Mountford P 《Chemical communications (Cambridge, England)》2008,(41):5101-5103
The first structurally authenticated [2+2] cycloaddition products of any transition metal hydrazide complexes are reported; cycloaddition products of transition metal hydrazides with alkynes and heteroalkynes have been obtained for the first time; these are the first structurally authenticated cycloaddition products for any transition metal M=NNR(2) functional group. 相似文献
7.
Helena Uceta Dr. María Vizuete Dr. José R. Carrillo Dr. Myriam Barrejón Prof. José Luis G. Fierro Dr. Maria Pilar Prieto Prof. Fernando Langa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(64):14644-14650
Density functional theory (DFT) studies of the interaction between graphene sheets and nitrile oxides have proved the feasibility of the reaction through 1,3-dipolar cycloaddition. The viability of the approach has been also confirmed experimentally through the cycloaddition of few-layer exfoliated graphene and nitrile oxides containing functional organic groups with different electronic nature. The cycloaddition reaction has been successfully achieved in one-pot from the corresponding oximes under microwave (MW) irradiation. The successful formation of the isoxazoline ring has been confirmed by Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). 相似文献
8.
Tamura O Mitsuya T Huang X Tsutsumi Y Hattori S Ishibashi H 《The Journal of organic chemistry》2005,70(26):10720-10725
[reaction: see text] Intramolecular cycloaddition of novel 1,3-dipoles, N-boranonitrones, was examined. Treatment of O-tert-butyldimethylsilyloximes 9-12 having olefin moieties with 2 equiv of BF3 x OEt2 generated N-boranonitrones, which underwent intramolecular cycloaddition to afford N-nonsubstituted cycloadducts 16 (and/or 18) after extractive workup. Despite the Lewis-acidic conditions, the olefin geometry of the substrates was retained in the cycloadducts in the present cycloaddition. The electronic nature of the N-boranonitrones appeared to be electrophilic. In the case of substrate 11c, having an electron-donating methyl group at an internal position of the olefin moiety, the cycloaddition gave the bridged cycloadduct 18b. The cycloaddition proceeded at relatively low temperature, and the diastereoselectivity was high. 相似文献
9.
The product 2 in the 1,3-dipolar cycloaddition of one equivalent of diazomethane to p-toluquinone (1) was determined by 250 MHz nmr spectra to be approximately 85% 6-methyl-1-H-indazole-4,7-dione (2b). X-ray crystallographic analysis was employed in the characterization of 1,6-dimethyl-1-H-indazole-4,7-dione (4a), which was the major 1-N-methyl regioisomer in the methylation of the cycloaddition mixture 2 with diazomethane. Methylation of the cycloaddition product 2 with diazomethane also provided a regioisomeric mixture of the 2-N-methyl derivatives 5. This mixture was synthesized for characterization by an independent method which utilized the cycloaddition of 3-methylsydnone (10) to toluquinone (1). 1,5,6-Trimethyl-1-H-ind-azole-4,7-dione (9) was found to be a minor product in the reaction of diazomethane with the cycloaddition product 2. 相似文献
10.
Baik J Kim M Park CY Kim Y Ahn JR An KS 《Journal of the American Chemical Society》2006,128(26):8370-8371
We first found experimentally a cycloaddition reaction of a molecule on a symmetry Si pair, 1,3-butadiene on the Si adatom pair of Si(111)7x7, while up to now only asymmetric Si pairs were reported to be involved in cycloaddition reactions on Si surfaces. As the symmetry of a Si pair is expected to influence significantly a cycloaddition product and a reaction pathway, the [4+2]-like cycloaddition product of 1,3-butadiene on the Si adatom pair is suggested to form through a concerted reaction pathway in comparison to a stepwise reaction pathway, which is favorable in the formation of the [4+2]-like cycloaddition product on the asymmetric Si pair (the Si adatom-restatom pair). 相似文献
11.
为研究纳米线的形成机理,通过密度泛函理论(DFT)研究了贵金属(铂)在脱质子化1,3-环加成石墨烯上的吸附.研究发现:(1)吸附在1,3-环加成石墨烯上的铂原子引起该结构的脱质子化过程并形成脱质子化1,3-环加成石墨烯;(2)贵金属在脱质子化1,3-环加成石墨烯上的锚定位是氮原子邻位的碳原子,这在邻位碳原子的平均巴德电荷分析(高达1.0e)中得到进一步的证实;(3)铂原子在相邻的脱质子化吡啶炔单元上形成金属纳米线,并且该纳米线比相应的铂团簇稳定得多;(4)电子结构分析表明,铂的吸附并没有从根本上改变脱质子化1,3-环加成石墨烯的电子性质.铂金属的掺杂使得Pt6团簇吸附形成的复合物呈现金属性,而Pt6纳米线形成的复合物则为半金属性. 相似文献
12.
This paper describes a novel route to functionalized piperidines via a formal [3+3] cycloaddition reaction of activated aziridines and palladium-trimethylenemethane (Pd-TMM) complexes. The cycloaddition reaction generally proceeds enantiospecifically with ring opening at the least hindered site of the aziridine. Therefore, readily available enantiomerically pure 2-substituted aziridines can be utilized to prepare enantiomerically pure 2-substituted piperidines in good to excellent yield. The N-substituent on the aziridine proved to be crucial to the success of this reaction with only 4-toluenesulfonyl (Ts) and 4-methoxybenzenesulfonyl (PMBS) aziridines permitting smooth cycloaddition to take place. Additionally, spirocyclic aziridines have been found to participate in the [3+3] cycloaddition reaction, whereas 2,3-disubstituted aziridines can be applied to provide fused bicyclic piperidines, albeit in low yield. 相似文献
13.
Hayashi Y Gotoh H Honma M Sankar K Kumar I Ishikawa H Konno K Yui H Tsuzuki S Uchimaru T 《Journal of the American Chemical Society》2011,133(50):20175-20185
Diphenylprolinol silyl ether was found to be an effective organocatalyst for promoting the asymmetric, catalytic, intramolecular [6 + 2] cycloaddition reactions of fulvenes substituted at the exocyclic 6-position with a δ-formylalkyl group to afford synthetically useful linear triquinane derivatives in good yields and excellent enantioselectivities. The cis-fused triquinane derivatives were obtained exclusively; the trans-fused isomers were not detected among the reaction products. The intramolecular [6 + 2] cycloaddition occurs between the fulvene functionality (6π) and the enamine double bond (2π) generated from the formyl group in the substrates and the diphenylprolinol silyl ether. The absolute configuration of the reaction products was determined by vibrational circular dichroism. The reaction mechanism was investigated using molecular orbital calculations, B3LYP and MP2 geometry optimizations, and subsequent single-point energy evaluations on model reaction sequences. These calculations revealed the following: (i) The intermolecular [6 + 2] cycloaddition of a fulvene and an enamine double bond proceeds in a stepwise mechanism via a zwitterionic intermediate. (ii) On the other hand, the intramolecular [6 + 2] cycloaddition leading to the cis-fused triquinane skeleton proceeds in a concerted mechanism via a highly asynchronous transition state. (iii) The fulvene functionality and the enamine double bond adopt the gauche-syn conformation during the C-C bond formation processes in the [6 + 2] cycloaddition. (iv) The energy profiles calculated for the intramolecular reaction explain the observed exclusive formation of the cis-fused triquinane derivatives in the [6 + 2] cycloaddition reactions. The reasons for the enantioselectivity seen in these [6 + 2] cycloaddition reactions are also discussed. 相似文献
14.
Kang T Kim WY Yoon Y Kim BG Lee HY 《Journal of the American Chemical Society》2011,133(45):18050-18053
A tandem reaction strategy for forming triquinanes from linear allenyl diazo compounds through an intramolecular 1,3-dipolar cycloaddition reaction of an allenyl diazo group that generates a trimethylenemethane (TMM) diyl followed by an intramolecular [2 + 3] TMM diyl cycloaddition reaction has been developed. The new tandem cycloaddition reaction is readily applicable to the synthesis of complex molecules with high versatility and efficiency. 相似文献
15.
Methodology has been sought towards obtaining a 2-chloro-1,4-naphthoquinone bearing hydroxyl groups in the adjoining ring for obtaining either kermesic or carminic acids. In the first of these objectives, kermesic acid has been synthesised from 6-chloro-2,5,8-trihydroxynaphtho-1,4-quinone by the regioselective cycloaddition of the 1,2-diacetate formed by its acetylation-aided tautomerism and cycloaddition with (E)- and (Z)-3-alkoxycarbonyl-2,4-bis(trimethylsilyloxy)penta-1,3-dienes. The parent unacetylated quinone resists cycloaddition. 相似文献
16.
1,3-Dipolar cycloaddition of C-aryl-N-phenylnitrones to 3,5-bis-(arylidene)-1-methylpiperidin-4-ones affords novel mono- and bis-spiroisoxazolidines in moderate yields. In general, this reaction predominantly yields mono-spiroisoxazolidine, wherein the oxygen of the nitrone is linked to the β-carbon of the benzylidene moiety, while 3,5-bis-(2-chloro- and 3-nitro-benzylidene)-1-methylpiperidin-4-ones afford predominantly bis-spiroisoxazolidines. The cycloaddition of mono-spiroisoxazolidines occurs with facial diastereoselectivity to furnish bis-spiroisoxazolidines. The nitrogen in the heterocyclic ring of the 3,5-bis-(arylidene)-1-methylpiperidin-4-ones facilitates the cycloaddition through transannular (NCO) and/or homoconjugative (NCC) interactions. 相似文献
17.
Total synthesis of ceratopicanol ( 1 ) was achieved with a tandem cycloaddition reaction of allenyl diazo compound 6 via a trimethylenemethane (TMM) diyl intermediate. The TMM diyl mediated [2+3] cycloaddition reaction furnished the consecutive quaternary carbon centers and showed an unusual diastereoselectivity. 相似文献
18.
Ronan Le Vzouët Andrew J.P. White Jeremy N. Burrows Anthony G.M. Barrett 《Tetrahedron》2006,62(52):12252-12263
Both (1) furan–maleimide Diels–Alder cycloaddition reaction and (2) furan–benzyne cycloaddition, Suzuki cross-coupling, boron-mediated aldol, and electrophilic aromatic substitution reactions were examined for the construction of the CDEF ring system of lactonamycin (1). 相似文献
19.
Suga H Ebiura Y Fukushima K Kakehi A Baba T 《The Journal of organic chemistry》2005,70(26):10782-10791
[reactions: see text] 1,3-Dipolar cycloaddition reactions between imines and carbonyl ylides generated by tandem intramolecular carbenoid-carbonyl cyclizations were found to be effectively catalyzed by Lewis acids (10 mol %). The Rh2(OAc)4-catalyzed reactions of o-(methoxycarbonyl)-alpha-diazoacetophenone with imines such as N-[2-(benzyloxy)benzylidene]aniline in the absence of Lewis acid gave no 1,3-dipolar cycloaddition products, but rather the dimeric product of the corresponding carbonyl ylide. In contrast, in the presence of Lewis acids such as Yb(OTf)3, the 1,3-dipolar cycloaddition reactions of the corresponding 1-methoxy-2-benzopyrylium-4-olate proceeded smoothly with several imines, giving in most cases exo-selectivity and no formation of the dimeric product. When Yb(OTf)3 was used as a Lewis acid catalyst, a fundamental catalytic effect was also observed in the cycloaddition reactions of imines with carbonyl ylides generated from 1-diazo-5-phenyl-2,5-pentanedione, 1-diazo-2,5-hexanedione and diazomethyl 2,3,4,5-tetrachloro-6-methoxycarbonylphenly ketone. This efficient catalytic effect can be satisfactorily explained in terms of energetics of the cycloaddition in the absence and the presence of Lewis acid by calculations using the ONIOM (B3LYP/6-31G(d):PM3) method. 相似文献
20.
Gas-phase reactions of acylium ions with alpha,beta-unsaturated carbonyl compounds were investigated using pentaquadrupole multiple-stage mass spectrometry. With acrolein and metacrolein, CH(3)-C(+)(double bond)O, CH(2)(double bond)CH-C(+)(double bond)O, C(6)H(5)-C(+)(double bond)O, and (CH(3))(2)N-C(+)(double bond)O react to variable extents by mono and double polar [4 + 2(+)] Diels-Alder cycloaddition. With ethyl vinyl ketone, CH(3)-C(+)(double bond)O reacts exclusively by proton transfer and C(6)H(5)-C(+)(double bond)O forms only the mono cycloadduct whereas CH(2)(double bond)CH-C(+)(double bond)O and (CH(3))(2)N-C(+)(double bond)O reacts to great extents by mono and double cycloaddition. The positively charged acylium ions are activated O-heterodienophiles, and mono cycloaddition occurs readily across their C(+)(double bond)O bonds to form resonance-stabilized 1,3-dioxinylium ions which, upon collisional activation, dissociate predominantly by retro-addition. The mono cycloadducts are also dienophiles activated by resonance-stabilized and chemically inert 1,3-dioxonium ion groups, hence they undergo a second cycloaddition across their polarized C(double bond)C ring double bonds. (18)O labeling and characteristic dissociations displayed by the double cycloadducts indicate the site and regioselectivity of double cycloaddition, which are corroborated by Becke3LYP/6-311++G(d,p) calculations. Most double cycloadducts dissociate by the loss of a RCO(2)COR(1) molecule and by a pathway that reforms the acylium ion directly. The double cycloadduct of the thioacylium ion (CH(3))(2)N-C(+)(double bond)S with acrolein dissociates to (CH(3))(2)N-C(+)(double bond)O in a sulfur-by-oxygen replacement process intermediated by the cyclic monoadduct. The double cycloaddition can be viewed as a charge-remote type of polar [4 + 2(+)] Diels-Alder cycloaddition reaction. 相似文献