- Gold(I)-Catalyzed Cascade Hydroarylation/Cycloaromatization to Indolizines via Pyridine Ring Construction
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An efficient and atom-economic method for the synthesis of multisubstituted indolizines via gold-catalyzed cascade hydroarylation/cycloaromatization reaction of α-(N-pyrrolyl)ketones with alkynes is described. The reaction is realized through the construction of the pyridine ring of indolizines, which allows the regioselective incorporation of a wide range of functionalities on the pyridine unit.
- Li, Xiangdong,Xie, Xin,Liu, Yuanhong
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Read Online
- Unexpected transformations of O-vinylacetophenone oxime in the system ButOK - THF
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Transformation of O-vinylacetophenone oxime in the system ButOK - THF was studied. The reaction at 60-65°C was shown to afford not the anticipated 2-phenylpyrrole, but, instead, 2,4-diphenylpyrrole (21% yield) and oligomer products (40% yield). The latter have the same elemental composition as the starting O-vinyl oxime but do not contain vinyloxy groups or pyrrole fragments.
- Trofimov,Tarasova,Shmidt,Mikkaleva,Sinegovskaya
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Read Online
- Efficient Far-Red/Near-IR Absorbing BODIPY Photocages by Blocking Unproductive Conical Intersections
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Photocages are light-sensitive chemical protecting groups that give investigators control over activation of biomolecules using targeted light irradiation. A compelling application of far-red/near-IR absorbing photocages is their potential for deep tissue activation of biomolecules and phototherapeutics. Toward this goal, we recently reported BODIPY photocages that absorb near-IR light. However, these photocages have reduced photorelease efficiencies compared to shorter-wavelength absorbing photocages, which has hindered their application. Because photochemistry is a zero-sum competition of rates, improvement of the quantum yield of a photoreaction can be achieved either by making the desired photoreaction more efficient or by hobbling competitive decay channels. This latter strategy of inhibiting unproductive decay channels was pursued to improve the release efficiency of long-wavelength absorbing BODIPY photocages by synthesizing structures that block access to unproductive singlet internal conversion conical intersections, which have recently been located for simple BODIPY structures from excited state dynamic simulations. This strategy led to the synthesis of new conformationally restrained boron-methylated BODIPY photocages that absorb light strongly around 700 nm. In the best case, a photocage was identified with an extinction coefficient of 124000 M-1 cm-1, a quantum yield of photorelease of 3.8%, and an overall quantum efficiency of 4650 M-1 cm-1 at 680 nm. This derivative has a quantum efficiency that is 50-fold higher than the best known BODIPY photocages absorbing >600 nm, validating the effectiveness of a strategy for designing efficient photoreactions by thwarting competitive excited state decay channels. Furthermore, 1,7-diaryl substitutions were found to improve the quantum yields of photorelease by excited state participation and blocking ion pair recombination by internal nucleophilic trapping. No cellular toxicity (trypan blue exclusion) was observed at 20 μM, and photoactivation was demonstrated in HeLa cells using red light.
- Shrestha, Pradeep,Dissanayake, Komadhie C.,Gehrmann, Elizabeth J.,Wijesooriya, Chamari S.,Mukhopadhyay, Atreyee,Smith, Emily A.,Winter, Arthur H.
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supporting information
p. 15505 - 15512
(2020/10/20)
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- Base-promoted ring-closing carbonyl-allene metathesis for the synthesis of 2,4-disubstituted pyrroles
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A base-promoted ring-closing carbonyl-allene metathesis reaction of N-allenyl β-enaminones (generated in situ from N-propargyl β-enaminones) gives 2,4-disubstituted pyrroles with cleavage of the C(sp)-C(sp3) bond. This transition metal-free procedure generates 1 equiv. of acetic acid as the sole byproduct. A preliminary mechanistic study supports a stepwise [2 + 2] cycloaddition/retro [2 + 2] reaction pathway.
- Cheng, Guolin,Lv, Weiwei,Xue, Lulu
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p. 4414 - 4417
(2018/10/17)
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- Preparation method of 2,4-di-substituted pyrrole derivative
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The invention discloses a preparation method of a 2,4-di-substituted pyrrole derivative. The reaction equation is shown in the description. By adopting the method, a pyrrole derivative with a plurality of substituents which is difficult to obtain with other methods can be synthesized.
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Paragraph 0020; 0021; 0022; 0023
(2018/07/30)
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- Ytterbium-mediated synthesis of 2,4-diarylpyrroles from α-bromo oxime ethers
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A novel and efficient ytterbium promoted reductive cyclisation dimerization of α-bromo-oxime ethers affording 2,4-diarylpyrroles with high regioselectivity has been developed. Compared with the reported synthesis methods, the method has the following advantages: readily available and safe starting material, one-pot single step operation and mild and neutral reaction conditions.
- Zhang, Xinxin,Zheng, Songlin,Zhang, Songlin
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p. 54254 - 54257
(2017/12/05)
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- α-Unsubstituted Pyrroles by NHC-Catalyzed Three-Component Coupling: Direct Synthesis of a Versatile Atorvastatin Derivative
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A practical one-pot cascade reaction protocol provides direct access to valuable 1,2,4-trisubstituted pyrroles. The process involves an N-heterocyclic carbene (NHC)-catalyzed Stetter-type hydroformylation using glycolaldehyde dimer as a novel C1 building-block, followed by a Paal-Knorr condensation with primary amines. The reaction makes use of simple and commercially available starting-materials and catalyst, an important feature regarding applicability and utility. Low catalyst loading under mild reaction conditions afforded a variety of 1,2,4-substituted pyrroles in a transition-metal-free reaction with high step economy and good yields. This methodology is applied in the synthesis of a versatile Atorvastatin precursor, in which a variety of modifications at the pyrrole core structure are possible.
- Fleige, Mirco,Glorius, Frank
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supporting information
p. 10773 - 10776
(2017/08/22)
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- Stepwise iododesilylation and coupling reaction: A flexible route to 2,4-disubstituted-1H-pyrroles
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In this study, we report a new strategy for the synthesis of 2,4-disubstituted pyrroles using a stepwise iododesilylation and palladium-catalysed Suzuki coupling reaction of 2,4-bis(trimethylsilyl)-1-t-Boc-1H-pyrrole (2). The regioselective iodo-desilylation followed by the Suzuki coupling reaction with concomitant Boc deprotection are critical aspects of the new synthesis method.
- Liu, Jianhui,Fu, Nanyan,Wei, Changyun,Song, Zhucao
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p. 2530 - 2532
(2016/05/24)
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- Reaction between 4-Nitro-1,3-diarylbutan-1-ones and Ammonium Acetate in the Presence of Morpholine and Sulfur: An Efficient Synthesis of 2,4-Diarylpyrroles
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An efficient synthesis of 2,4-diarylpyrroles is described. Heating a mixture of a 4-nitro-1,3-diarylbutan-1-one and ammonium acetate in the presence of morpholine and sulfur afforded the corresponding 2,4-diarylpyrroles in excellent yields.
- Adib, Mehdi,Ayashi, Neda,Heidari, Fatemeh,Mirzaei, Peiman
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p. 1738 - 1742
(2016/07/06)
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- MANUFACTURING METHOD OF DIPYRRYL KETONES AND DIPYRRYL KETONES MADE BY THE SAME
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The present invention relates to a manufacturing method of a dipyrryl ketone and dipyrryl ketone manufactured by the method wherein the manufacturing method of dipyrryl ketone is allowed to manufacture dipyrryl ketone from 2-carboxylic acid pyrrole compounds in a high yield with use of a simple process.COPYRIGHT KIPO 2015
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Paragraph 0122; 0123; 0137-0139
(2016/12/01)
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- Synthesis of multisubstituted 1H-pyrrole: Selenium-catalyzed reaction of γ-nitro substituted carbonyl compounds and carbon monoxide
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The novel and efficient selenium-catalyzed reductive N-heterocyclization of γ-nitro substituted carbonyl compounds with carbon monoxide has been developed. Various multisubstituted 1H-pyrroles can be easily prepared by this protocol. The one-pot synthesis
- Umeda, Rui,Mashino, Tsukasa,Nishiyama, Yutaka
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p. 4395 - 4399
(2014/06/10)
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- Simple two-step synthesis of 2,4-disubstituted pyrroles and 3,5-disubstituted pyrrole-2-carbonitriles from enones
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The cyclocondensation of enones with aminoacetonitrile furnishes 3,4-dihydro-2H-pyrrole-2-carbonitriles which can be readily converted to 2,4-disubstituted pyrroles by microwave-induced dehydrocyanation. Alternatively, oxidation of the intermediates produ
- Kucukdisli, Murat,Ferenc, Dorota,Heinz, Marcel,Wiebe, Christine,Opatz, Till
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supporting information
p. 466 - 470
(2014/03/21)
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- Synthesis of 2,2′-dipyrryl ketones from pyrrole-2-carboxylic acids with trifluoroacetic anhydride
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An efficient synthesis of 2,2′-dipyrryl ketones has been carried out from pyrrole-2-carboxylic acids using trifluoroacetic anhydride (TFAA). Simultaneous generation of both mixed anhydride and 2-unsubstituted pyrrole, via facile decarboxylation with in-si
- Kim, Se Hee,Lim, Jin Woo,Yu, Jin,Kim, Jae Nyoung
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p. 2604 - 2608
(2013/10/22)
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- Catalytic activation of carbohydrates as formaldehyde equivalents for stetter reaction with enones
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We disclose the first catalytic activation of carbohydrates as formaldehyde equivalents to generate acyl anions as one-carbon nucleophilic units for a Stetter reaction. The activation involves N-heterocyclic carbene (NHC)-catalyzed C-C bond cleavage of carbohydrates via a retro-benzoin-type process to generate the acyl anion intermediates. This Stetter reaction constitutes the first success in generating formal formaldehyde-derived acyl anions as one-carbon nucleophiles for non-self-benzoin processes. The renewable nature of carbohydrates, accessible from biomass, further highlights the practical potential of this fundamentally interesting catalytic activation.
- Zhang, Junmin,Xing, Chong,Tiwari, Bhoopendra,Chi, Yonggui Robin
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p. 8113 - 8116
(2013/07/19)
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- 2,4- vs 3,4-disubsituted pyrrole synthesis switched by copper and nickel catalysts
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A novel and efficient copper or nickel catalyzed highly selective denitrogenative annulation of vinyl azides with aryl acetaldehydes has been developed. 2,4- and 3,4-diaryl substituted pyrroles, which are difficult to synthesize by the reported methods, can be highly regioselectively prepared by this protocol simply switched by the selection of the transition metal catalysts. Compared with the reported acidic or basic conditions for polysubstituted pyrrole synthesis, the present reaction conditions are mild, neutral, and very simple without any additives.
- Chen, Feng,Shen, Tao,Cui, Yuxin,Jiao, Ning
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supporting information
p. 4926 - 4929,4
(2012/12/12)
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- Enone-alkyne reductive coupling: A versatile entry to substituted pyrroles
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The reductive coupling of enones or enals with alkynes, followed by olefin oxidative cleavage and Paal-Knorr cyclization, provides a versatile entry to a variety of pyrrole frameworks. A number of limitations of alternate entries to the requisite 1,4-dica
- Thompson, Benjamin B.,Montgomery, John
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p. 3289 - 3291
(2011/09/13)
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- Conformationally restricted aza-BODIPY: Highly fluorescent, stable near-infrared absorbing dyes
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Novel NIR fluorescent, conformational restricted aza-dipyrromethene boron difluoride (aza-BODIPY) dyes were prepared by an efficient process. Such conformational restricted aza-BODIPY dyes possess intense absorption, strong fluorescence, high chemical and
- Zhao, Weili,Carreira, Erick M.
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p. 7254 - 7263
(2007/10/03)
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- A modular synthesis of unsymmetrical tetraarylazadipyrromethenes
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A stepwise route to unsymmetrical tetraarylazadipyrromethenes by a condensation of 2,4-diaryl-5-nitroso-pyrroles with 2,4-diarylpyrroles is described. This modular building-block approach allows for the introduction of up to four different aryl substituents on the azadipyrromethene and is tolerant of a varied substituent set. An efficient synthesis of the 2,4-diarylpyrroles building blocks from 1,3-diaryl-4-nitro-butan-1-ones by nitro hydrolysis to a keto-aldehyde and subsequent ammonia condensation reaction has been achieved. The facile conversion of 2,4-diarylpyrroles into their α-nitroso analogues by their reaction with sodium nitrite generated the second building block required for the synthesis.
- Hall, Michael J.,McDonnell, Shane O.,Killoran, John,O'Shea, Donal F.
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p. 5571 - 5578
(2007/10/03)
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- SmI2-mediated reduction of phenacyl azides: A novel preparation of 2,4-diarylpyrroles
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A novel reductive cyclisation of phenacyl azides brought about by samarium iodide is described in this paper. By this process several 2,4-diarylpyrroles have been prepared.
- Fan, Xuesen,Zhang, Xinying,Zhang, Yongmin
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p. 750 - 752
(2007/10/03)
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- SmI2-mediated synthesis of 2,4-diarylpyrroles from phenacyl azides
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A novel reduction of phenacyl azides induced by SmI2 was investigated and 2,4-diarylpyrroles were prepared in moderate to good yields under mild conditions.
- Fan, Xuesen,Zhang, Yongmin
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p. 1863 - 1865
(2007/10/03)
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- Rhodium-Catalysed Reactions of Propargylamines with CO/H2. Formation of Pyrroles and Butenolides
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Rhodium-catalysed reactions of (arylpropargyl)amines with CO/H2 give β-arylpyrroles in good yields.Reactions of (alkylpropargyl)amines gave alkylpyrroles together with butenolides which are formed in an unusual reaction that probably involves double carbonylation, reduction of one carbonyl function and removal of the amine function by hydrogenolysis.The single-crystal X-ray structure of 5-methyl-N,3-diphenylpyrrole-2-carboxamide is recorded.
- Campi, Eva M.,Fallon, Gary D.,Jackson, W. Roy,Nilsson, Ylva
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p. 1167 - 1178
(2007/10/02)
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- Zirconocene(iso-butyl) chloride: In situ generation of a zirconocene(methyl) chloride equivalent for use in organic synthesis
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Zirconocene(iso-butyl) chloride 1, which can be generated in situ from commercially available, inexpensive, and air-stable zirconocene dichloride, can function as a zirconocene(methyl) chloride equivalent.
- Barr,Watson,Buchwald
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p. 5465 - 5468
(2007/10/02)
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- A HYDROFORMYLATION ROUTE TO Β-SUBSTITUTED PYRROLES
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Rhodium catalysed hydroformylation of readily available β-alkynylamines gives 3-substituted or 2,4-disubstituted pyrroles in good yields.
- Campi, Eva M.,Jackson, W. Roy,Nilsson, Ylva
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p. 1093 - 1094
(2007/10/02)
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- SYNTHESIS OF ISOMERIC O-(PHENYLVINYL)-ACETOPHENONE OXIMES AND THEIR REARRANGEMENT TO PYRROLES
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Methods were developed for the regioselective synthesis of α- and β-O-(phenylvinyl)-acetophenone oximes.Their conversion to 2,5- and 2,4-diphenylpyrroles, respectively, confirms the mechanism of this process, including a step of -sigmatropic displace
- Yurovskaya, M. A.,Afanas'ev, A. Z.,Bundel', Yu. G.
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p. 875 - 877
(2007/10/02)
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- Conversions of N-Vinylpyridinium Cations into Tricyclic Cage Compounds
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1-Allyl-2,4,6-trimethyl- and 1-allyl-2,4,6-triphenylpyridinium cations are isomerized by mild alkali into the corresponding 1-propenylpyridinium cations.Strong base converts the latter and 1-vinyl-2,4,6-triphenylpyridinium cation salts into oxazatricyclononene isomers of the quaternary hydroxides.The elucidation of the structure and further transformations of the cage compounds are described.
- Katritzky, Alan R.,Rubio, Olga
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p. 448 - 454
(2007/10/02)
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- NOVEL TYPES OF TRANSFORMATIONS OF α-AZIDOSTYRENE DERIVATIVES AND 3-ARYL-2H-AZIRINES IN THE PRESENCE OF HEXACARBONYLMOLYBDENUM
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The reaction of α-azidostyrene derivatives with hexacarbonylmolybdenum was found to give 2,5-diarylpyrroles and acetophenone derivatives via a complexed 1-arylvinylnitrene intermediate, while that of 3-aryl-2H-azirines gave 2,4-diarylpyrroles in addition to acetophenone derivatives and 2,5-diarylpyrazines.
- Nitta, Makoto,Kobayashi, Tomoshige
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p. 1715 - 1718
(2007/10/02)
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