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1.
We have reported DBU-catalyzed one-pot synthesis of biologically and pharmacologically important spiropyrans from condensation of malononitrile/ethyl cyanoacetate, 1,3-dicarbonyl compounds, and ninhydrin/acenaphthequinone/istain in good yields. This new protocol employing DBU, which is a green, recyclable, and inexpensive catalyst, offers advantages such as mild reaction conditions, short reaction times, and easy isolation of products. The structures have been confirmed by x-ray analysis. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] 相似文献
2.
We have reported DBU catalyzed one-pot synthesis of 3,4-dihydropyrano[3,2-c]chromenes, dihydropyrano[4,3-b]pyranes, 2-amino-4H-benzo[h]chromenes and 2-amino-4H-benzo[g]chromenes from aldehydes, active methylene compounds malononitrile/ethyl cyanocacetate, and 4-hydroxycoumarin/4-hydroxy-6-methylpyrone/1-naphthol/2-hydroxynaphthalene-1,4-dione in water under reflux. The attractive features of this process are mild reaction conditions, reusability of the reaction media, short reaction times, easy isolation of products, and excellent yields. 相似文献
3.
Ye Eun Kim Yoo Jin Lim Chorong Kim Yu Ra Jeong Hyunsung Cho Sang Hyup Lee 《Molecules (Basel, Switzerland)》2022,27(19)
The syntheses of novel 1-acyloxyindole compounds 1 and the investigations on reaction pathways are presented. Nitro ketoester substrate 2, obtained in a two-step synthetic process, underwent reduction, intramolecular addition, nucleophilic 1,5-addition, and acylation to afford 1-acyloxyindoles 1 in one pot. Based on the systematic studies, we established the optimized reaction conditions for 1 focusing on the final acylation step of the intermediate 1-hydroxyindole 8. With the optimized conditions, we succeeded in synthesizing 21 examples of new 1-acyloxyindole derivatives 1 in modest yields (Y = 24 − 35%). Among the 1-acyloxyindole compounds, 1-acetoxyindole compounds 1x were generally unstable, and their yields were relatively lower than the other 1-acyloxyindoles. We expect that a bulkier alkyl or aromatic group on R2 could stabilize the 1-acyloxyindole compounds. Significantly, one-pot reactions of a four-step sequence successfully generated compounds 1 that are all new and might be difficult to be synthesized otherwise. 相似文献
4.
《Mendeleev Communications》2023,33(4):455-457
During attempts to involve 5-methyl-2-phenyl-1-(3-phenyl-prop-2-yn-1-yl)-1H-imidazole in a base-promoted, allene-mediated cyclization of the alkyne moiety onto the nearby aromatic ring, substantial amount of the ketone resulting from hydration of the alkyne with adventitious water was discovered. The formation of the ketone of the anti-Markovnikov alkyne hydration was developed into a preparative method. This method, alternative to the common acid-and metal-catalyzed approaches, may be of particular utility when alkyne hydration needs to be performed in the presence of acid-labile groups. 相似文献
5.
Phenolic sulfates protected with a trichloroethyl or trifluoroethyl group were rapidly and efficiently obtained by reacting phenols with sulfuryl imidazolium salts in the presence of DBU. Phenolic hydroxyl groups could be sulfated in good yield in the presence of aliphatic hydroxyl groups and multiple sulfations were also readily achieved. 相似文献
6.
Takuji Magata Saeka Nagano Takuya Endo Jun Kawaida Shiho Nagaoka Yoshimi Hirokawa Naoyoshi Maezaki 《Tetrahedron letters》2017,58(37):3628-3630
Methyl 2-[1-[(tert-butoxycarbonyl)amino]ethyl]-4-methyloxazole-5-carboxylate (1) was synthesized with high optical purity via a Pd–catalyzed amide coupling with vinyl triflate with subsequent oxazole formation. The latter reaction proceeds via bromination of an enamide with NBS and DBU-promoted cyclization. The oxazole subunit positional isomer in a macrocyclic azole peptide was obtained in a good yield without racemization. The scope and limitations of this reaction were also investigated. 相似文献
7.
N. F. Gol’dshleger A. N. Lapshin E. I. Yudanova N. M. Alpatova E. V. Ovsyannikova 《Russian Journal of Electrochemistry》2006,42(1):16-21
Using cyclic voltammetry, it is shown that formal reduction potentials of pyridyl-substituted pyrrolidinofullerenes are shifted to negative values as compared with formal potentials of the corresponding redoxtransitions of C60, which indicates weakening of the acceptor properties of the fullerene fragment. NIR spectrophotometric and EPR spectroscopic studies show that cis-2′,5′-di-(4-pyridinyl)pyrrolidino-[3′,4′:1,2][60]fullerene is reduced with 1,8-diazobicyclo[5.4.0]undec-7-ene and morpholine to give a radical anion. 相似文献
8.
Hiromu Kawakubo Tomoko Suzuki Kazutaka Nishino Futaba Hara Tomoyoshi Takano Yoshito Takebayashi 《合成通讯》2013,43(9):1068-1072
Diethyl azodicarboxylate (DEAD) is a well-known coupling reagent that can be readily synthesized from diethylhydrazodicarboxylate (DEHD). The bromination of commercially available ethyl allophanate (1) in CHCl3, followed by the Hofmann-type rearrangement reaction of the resulting N-brominated species 2 and 3 in C2H5OH in the presence of 1,8-diazabicyclo[5.4.0]-7-undecene (DBU), gave DEHD in good yield from a one-pot process. Interestingly, however, the bromination and Hofmann-type rearrangement reactions did not occur in the presence of N(C2H5)3. These results therefore suggest that this reaction is reliant upon a high level of reactivity during the bromination reaction to give 2 and 3, and that these N-brominated species require the presence of a strong and nonnucleophilic base to undergo the Hofmann-type rearrangement to give DEHD. 相似文献
9.
Synthesis, structures and some reactions of Ru(CCCCFc)(PP)Cp (PP = dppm, dppe) and related compounds
Michael I. Bruce Frédéric de Montigny Martyn Jevric Brian W. Skelton Allan H. White 《Journal of organometallic chemistry》2004,689(18):2860-2871
The compounds Ru(CCCCFc)(PP)Cp [PP = dppe (1), dppm (2)], have been obtained from reactions between RuCl(PP)Cp and FcCCCCSiMe3 in the presence of KF (1) or HCCCCFc and K[PF6] (2), both with added dbu. The dppe complex reacts with Co2(CO)6(L2) [L2 = (CO)2, dppm] to give 3, 4 in which the Co2(CO)4(L2) group is attached to the outer CC triple bond. The PPh3 analogue of 3 (5) has also been characterised. In contrast, tetracyanoethene reacts to give two isomeric complexes 6 and 7, in which the cyano-olefin has added to either CC triple bond. The reaction of RuCl(dppe)Cp with HCCCCFc, carried out in a thf/NEt3 mixture in the presence of Na[BPh4], gave [Ru{CCC(NEt3)CHFc}(dppe)Cp]BPh4 (8), probably formed by addition of the amine to an (unobserved) intermediate butatrienylidene [Ru(CCCCHFc)(dppe)Cp]+. The reaction of I2 with 8 proceeds via an unusual migration of the alkynyl group to the Cp ring to give [RuI(dppe){η-C5H4CCC(NEt3)CHFc}]I3 (9). Single-crystal X-ray structural determinations of 1, 2 and 4-9 are reported. 相似文献
10.
8-Bromobicyclo[5.1.0]oct-1(8)-cne (7), an intermediate for the preparation of 8-substituted bicyclo[5.1.0]oct-1(8)-enes, was synthesized by denomination of 1,8,8-tribromobicyclo[5.1.0]octane (6). Compound 7 underwent bromo-lithium exchange followed by nucleophilic substitution reactions to generate bicyclo[5.1.0]oct-1(8)-ene (5), 8-methylbicyclo[5.1.0]oct-1(8)-ene (10), and 8-trimethylsilylbicyclo[5.1.0]oct-1(8)-ene (11). The bicyclic cyclopropenes 7, 5, 10, and 11 reacted with cyclopentadiene to form adducts 12, 13, 14, and 15, respectively. All of these Diels-Alder adducts are endo-exo isomers (endo-addition from the view of the cyclopropene and exo-addition from the view of the cyclooctene). 相似文献
11.
Katsumi Inomata Shigeo Kawasaki Atsushi Kameyama Tadatomi Nishikubo 《Journal of polymer science. Part A, Polymer chemistry》2001,39(4):530-538
Novel multifunctional photopolymers with both pendant epoxy groups and phenacyl ester groups were synthesized by the one‐pot method for the reaction of poly(methacrylic acid) with epibromohydrin; this was followed by a reaction with phenacylbromide with 1,8‐diazabicyclo‐[5.4.0]undecene‐7 as a condensation reagent. These esterification reactions proceeded smoothly and quantitatively under mild conditions. Moreover, the photochemical reactions of the resulting polymers were evaluated by UV and IR spectroscopy. The pendant phenacyl ester groups were photocleaved to give corresponding carboxyl groups, and then the produced carboxyl groups reacted with pendant epoxy groups. Furthermore, the baking process promoted a crosslinking reaction because of the addition reaction of epoxy groups with carboxyl groups after irradiation. It was also proven that the photochemical reactivity of the resulting polymers was affected by the structure of the phenacyl ester group. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 530–538, 2001 相似文献
12.
The reaction of a variety of aldoximes with perfluoroalkanosulfonyl fluoride in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene(DBU) in dichloromethane smoothly generated the corresponding nitriles in 70%–95% yields. 相似文献
13.
14.
Olivier Coulembier Sébastien MoinsJean-Marie Raquez Franck MeyerLaetitia Mespouille Emmanuel DuquesnePhilippe Dubois 《Polymer Degradation and Stability》2011,96(5):739-744
1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) organic catalyst has generated a tremendous impact in the metal-free ring-opening polymerization of (di)lactones. Interestingly, its extraction after use has never been studied so far and a simple deactivation by addition of benzoic acid to generate the corresponding salt has always been supposed to kill its activity. This study reveals and highlights the importance of the work-up to remove or at least drastically limit the presence of the benzoic acid/DBU salt from poly(l-lactide). Three different extraction methods allowed us to conclude that a two-step work-up gathering liquid/liquid extractions and a drop by drop precipitation is highly required to keep the enantiomerically pure lactic acid polymer safe. If not perfectly extracted the benzoic acid/DBU salt has been proved to degrade the materials during a melt process even during a differential scanning calorimetry experiment. 相似文献
15.
Naoyuki Kawashima Atsushi Kameyama Tadatomi Nishikubo Takabumi Nagai 《Journal of polymer science. Part A, Polymer chemistry》2001,39(10):1764-1773
The donor–acceptor-type norbornadiene (D–A NBD) 1,4,5,6-tetramethyl-3-phenyl-2,5-NBD-2-carboxylic acid was prepared by the Diels–Alder reaction of methyl 3-phenylprop-2-ynoate with 1,2,3,4-tetramethyl-1,3-cyclopentadiene. 1,4,5,6,7-Pentamethyl-3-phenyl-2,5-NBD-2-carboxylic acid was also synthesized in the same way. Styrene-type polymers with pendant D–A NBD moieties were prepared with a 100% degree of substitution (DS) by the reaction of D–A NBD carboxylic acids with poly[(p-chloromethyl)styrene] with 1,8-diazabicyclo[5.4.0]undecene-7 in dimethyl sulfoxide at 70 °C for 6 h. In the reaction of D–A NBD carboxylic acids with poly(2-chloroethyl vinyl ether), the DSs were about 60%. The photochemical valence isomerizations of all the NBD polymers proceeded smoothly with UV irradiation in tetrahydrofuran solutions and in the film state. In addition, the rate of the photochemical reaction of the NBD polymers increased efficiently by the addition of 4,4′-bis(diethylamino)benzophenone as a photosensitizer in a film state. The stored thermal energy of the irradiated polymers was also evaluated by differential scanning calorimetry to be 55–74 kJ/mol. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1764–1773, 2001 相似文献
16.
Debromination of N‐benzyl 4‐ or 5‐substituted α‐bromo‐α‐p‐toluenesulfonylglutarimides is achieved with 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) to give the N‐benzyl 4‐ or 5‐substituted α‐p‐toluenesulfonylglutarimides. The DBU/THF system is applied to a new methodology for the synthesis of bicyclic glutarimide skeleton in moderate yields. 相似文献
17.
S. Y. S. Beheshtiha R. Hekmatshoar F. Soltani 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):1723-1729
A series of new 1,8-naphthylimide and 4-(thio)-7H-benzimidazo[2,1-a]benz[d,e]isoquinolin-7-one derivatives has been synthesized, and the UV/Vis absorptioin characteristics discussed. Substituents' effect on the UV/Vis absorption characteristics have been investigated. 相似文献
18.
A facile one-pot synthesis of N-fused 1,2,4-triazoles from heterocyclic hydrazines and aldehydes is reported. The reaction is efficiently promoted by chromium (VI) oxide to afford the desired products mostly in high yields and in relatively short time. The high yield of the products and short reaction time are notable advantages of the developed protocol. This protocol is effective toward various substrates having different functionalities. 相似文献
19.
New types of oxazolo[5,4-d]pyrimidines were synthesized via 1,8-diazabicyclo[5,4,0]undec-7-ene-catalyzed heteroannulation of 2-substituted 5-amino-4-cyano-1,3-oxazoles with various isothiocyanates. 相似文献
20.
Nakamura S Wada M Crabtree BL Reeves PM Montgomery JH Byrd HJ Harada S Kuroda N Nakashima K 《Analytical and bioanalytical chemistry》2007,387(6):1983-1990
A sensitive semi-micro column HPLC method with peroxyoxalate chemiluminescence (POCL) detection and column switching has been
developed for simultaneous determination of 3,4-methylenedioxymethamphetamine (MDMA) and related compounds, for example 3,4-methylenedioxyamphetamine,
methamphetamine, and amphetamine, in hair. After digestion of the hair with 1 mol L−1 sodium hydroxide the compounds were extracted with n-heptane and derivatized with 4-(N,N-dimethylaminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole. A mixture of hydrogen peroxide and bis(2,4,5-trichloro-6-carbopentoxyphenyl)oxalate
in acetonitrile was used as post-column CL reagent. Calibration plots showed linearity was good (r = 0.999); detection limits were 0.02–0.16 ng mg−1 hair at a signal-to-noise ratio of 3. The precision of the method, as RSD (n = 5), in intra-day and inter-day assays was better than 5.0 and 6.9%, respectively. The proposed method was sufficiently
sensitive to detect low ng mg−1 levels of MDMA and related compounds in hair, and could be used for quantification of the compounds in hair samples from
patients treated in a chemical dependency unit. 相似文献