- Multicomponent synthesis of polyphenols and their in vitro evaluation as potential β-amyloid aggregation inhibitors
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While plant polyphenols possess a variety of biological properties, exploration of chemical diversity around them is still problematic. Here, an example of application of the Ugi multicomponent reaction to the combinatorial assembly of artificial, yet “natural-like”, polyphenols is presented. The synthesized compounds represent a second-generation library directed to the inhibition of β-amyloid protein aggregation. Chiral enantiopure compounds, and polyphenol-β-lactam hybrids have been prepared too. The biochemical assays have highlighted the importance of the key pharmacophores in these compounds. A lead for inhibition of aggregation of truncated protein AβpE3-42 was selected.
- Galante, Denise,Banfi, Luca,Baruzzo, Giulia,Basso, Andrea,D’Arrigo, Cristina,Lunaccio, Dario,Moni, Lisa,Riva, Renata,Lambruschini, Chiara
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Read Online
- Microwave-promoted reaction of N-(alk-1-enyl)chloroacetamides with sodium azide unexpectedly yields 1H-imidazol-5(4H)-ones
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A novel method to prepare biologically relevant 1H-imidazol-5(4H)-ones from aliphatic amines, isobutyraldehyde, chloroacetyl chloride and sodium azide under microwave irradiation has been developed.
- Kantin, Grigory P.,Krasavin, Mikhail Yu.
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Read Online
- Retro-Ene Reactions of N-Substituted Derivatives of 4-Aza-2,2-dimethyl-1-phenyl-3-butenone and Related Compounds
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The retro-ene reactions of N-substituted derivatives of 4-aza-2,2-dimethyl-1-phenyl-3-butenone with methanol and benzylamine are described.The reactions with methanol yield methyl benzoate and N-substituted derivatives of 2-methylpropanimine.Reaction of N-benzyl-4-aza-2,2-dimethyl-1-phenyl-3-butenone with benzylamine yields N-benzyl-2-methyl-1-phenylpropanimine and N,N'-dibenzylformamidine.
- Armesto, Diego,Horspool, William M.,Perez-Ossorio, Rafael,Ramos, Ana
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Read Online
- Enantioselective Reductive Cyanation and Phosphonylation of Secondary Amides by Iridium and Chiral Thiourea Sequential Catalysis
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The combination of transition-metal catalysis and organocatalysis increasingly offers chemists opportunities to realize diverse unprecedented chemical transformations. By combining iridium with chiral thiourea catalysis, direct enantioselective reductive cyanation and phosphonylation of secondary amides have been accomplished for the first time for the synthesis of enantioenriched chiral α-aminonitriles and α-aminophosphonates. The protocol is highly efficient and enantioselective, providing a novel route to the synthesis of optically active α-functionalized amines from the simple, readily available feedstocks. In addition, the reactions are scalable and the thiourea catalyst can be recycled and reused.
- Chen, Dong-Huang,Sun, Wei-Ting,Zhu, Cheng-Jie,Lu, Guang-Sheng,Wu, Dong-Ping,Wang, Ai-E,Huang, Pei-Qiang
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supporting information
p. 8827 - 8831
(2021/03/16)
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- Base-Free Oxidative Coupling of Amines and Aliphatic Alcohols to Imines over Au–Pd/ZrO2 Catalyst under Mild Conditions
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Abstract: The base-free synthesis of imines from amines and aliphatic alcohols over Au–Pd alloy catalysts under ambient conditions was developed. A series of Au–Pd/ZrO2 bimetallic catalysts with varying metal loadings and Au?:?Pd molar ratios were prepared and their catalytic performance was investigated. The 3.0?wt?% Au–Pd/ZrO2 alloy catalyst with Au?:?Pd molar ratio of 1?:?1 showed the best catalytic performance. Under air atmosphere, various imines were obtained from coupling of amines and aliphatic alcohols without any additives or promoters. The performance of alloy NPs was superior to that of monometallic catalysts due to the synergistic effect which was demonstrated by TEM, XPS, and UV–Vis characterization. Our work suggested this transformation differed slightly from those reactions between amine and benzyl alcohol and a possible mechanism was proposed. Moreover, the Au–Pd/ZrO2 catalyst could be easily separated and reused for at least five successive runs with high catalytic activity.
- Cui, Wenjing,Jia, Meilin,Sagala,Wang, Jiang
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p. 958 - 967
(2021/06/06)
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- Activation of primary amines by copper(i)-based lewis acid promoters in the solventless synthesis of secondary propargylamines
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Primary amines are activated by copper(I)-based Lewis acid promoters in an A 3 -coupling one-pot solventless reaction with aldehydes and phenylacetylene for the synthesis of secondary propargylamines. The reaction is promoted by a CuSO 4 /NaI system, a practical precursor of the in situ generated effective CuI/I 2 system, that worked well, but only in a restricted number of examples. Substitution of I 2 with CeCl 3 ·7H 2 O in a one-pot two-step reaction provided good yields and a wider applicability, with the added value given by a safer procedure.
- Cimarelli, Cristina,Navazio, Federica,Rossi, Federico V.,Del Bello, Fabio,Marcantoni, Enrico
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p. 2387 - 2396
(2019/05/27)
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- Nucleophilic Imines and Electrophilic o-Quinone Methides, a Three-Component Assembly of Assorted 3,4-Dihydro-2 H-1,3-benzoxazines
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A one-pot method for joining three separate components leading to an assortment of N-substituted 3,4-dihydro-2H-1,3-benzoxazines is described. The method involves the addition of a Grignard reagent to an o-OBoc salicylaldehyde in the presence of an imine. With a variety of components, 15 examples are presented, including the diastereoselective incorporation of chiral imines.
- Chen, Peishan Kc,Wong, Yuk Fai,Yang, Derek,Pettus, Thomas R. R.
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supporting information
p. 7746 - 7749
(2019/10/11)
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- Unusually Reactive Cyclic Anhydride Expands the Scope of the Castagnoli-Cushman Reaction
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In the course of synthesizing and testing various "azole-including" cyclic anhydrides in the Castagnoli-Cushman reaction with imines, a remarkably reactive, pyrrole-based anhydride has been identified. It displayed a remarkably efficient reaction with N-alkyl and N-aryl imines, in particular, with "enolizable" α-C-H imines which typically fail to react with a majority of known cyclic anhydrides. The reactivity of this anhydride has been justified by an efficient resonance stabilization of its enol form. This finding expands the existing arsenal of highly reactive cyclic anhydrides and further confirms the importance of anhydride enolization for an efficient Castagnoli-Cushman reaction.
- Chizhova, Maria,Khoroshilova, Olesya,Dar'In, Dmitry,Krasavin, Mikhail
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p. 12722 - 12733
(2018/10/15)
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- Beyond the five and six: Evaluation of seven-membered cyclic anhydrides in the castagnoli-cushman reaction
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The Castagnoli-Cushman reaction with benzo[d]- oxepine-2,4(1H,5H)-dione as an anhydride component allowed for preparation of 2,3-disubstituted 4-oxo-2,3,4,5-tetrahydro-1H-benzo[d]- azepine-1-carboxylic acids in 21-75% yields and with good trans diastereoselectivity. The method worked with imines generated from aromatic or a-branched aliphatic aldehydes and is amenable for both parallel synthesis and scale-up. The procedure for epimerization of the resulting trans-disubstituted tetrahydrobenzo[d]azepines to their cis isomers was also developed.
- Adamovskyi, Mykhailo I.,Ryabukhin, Sergey V.,Sibgatulin, Dmitriy A.,Rusanov, Eduard,Grygorenko, Oleksandr O.
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supporting information
p. 130 - 133
(2017/09/08)
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- Fluorinated matrix metalloproteinases inhibitors - Phosphonate based potential probes for positron emission tomography
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Fluorine-containing inhibitors of matrix metalloproteinases (MMPs) can serve as lead structures for the development of 18F-labeled radioligands. These compounds might be useful as non-invasive imaging probes to characterize pathologies associated with increased MMP activity. Results with a series of fluorinated analogs of a known biphenyl sulfonamide inhibitor have shown that fluorine can be incorporated into two different positions of the molecular scaffold without significant loss of potency in the nanomolar range. Additionally, the potential of a hitherto unknown fluorinated tertiary sulfonamide as MMP inhibitor has been demonstrated.
- Beutel, Bernd,Daniliuc, Constantin G.,Riemann, Burkhard,Sch?fers, Michael,Haufe, Günter
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supporting information
p. 902 - 909
(2016/02/10)
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- Synthesis of imines from amines in aliphatic alcohols on Pd/ZrO2 catalyst under ambient conditions
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Synthesis of imines from amines and aliphatic alcohols (C 1-C6) in the presence of base on supported palladium nanoparticles has been achieved for the first time. The catalytic system shows high activity and selectivity in open air at room temperature.
- Cui, Wenjing,Zhaorigetu, Bao,Jia, Meilin,Ao, Wulan,Zhu, Huaiyong
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p. 2601 - 2604
(2014/01/06)
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- Gold-catalyzed oxidative rearrangement involving 1,2-acyl migration: Efficient synthesis of functionalized dihydro-γ-carbolines from α-(2-indolyl) propargylic alcohols and imines
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Smooth moves with a nifty side step: A gold-catalyzed transformation of α-(2-indolyl) propargylic alcohols with imines in the presence of the oxidant 8-isopropylquinoline N-oxide provided rapid access to highly functionalized dihydro-γ-carbolines (see scheme). The reaction mechanism is proposed to involve intermolecular trapping of an α-carbonyl gold carbenoid intermediate, followed by cyclization and a novel gold-assisted 1,2-acyl migration.
- Wang, Lu,Xie, Xin,Liu, Yuanhong
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supporting information
p. 13302 - 13306
(2014/01/06)
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- Synthesis of α, α-dideutero-β-amino esters
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A straight forward entry to α, α-dideutero-β-amino esters starting from the corresponding imines and deuterated acetonitrile has been developed involving a two-step process.
- Chandrasekhar,Pendke, Mrunal,Muththe, Chandrashekar,Akondi, Srirama Murthy,Mainkar, Prathama S.
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experimental part
p. 1292 - 1295
(2012/03/27)
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- Regioselective photochemical rearrangement of N-mesyloxylactams
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N-Mesyloxylactams can undergo ring contraction either by C-3 (usually observed) or C-5 migration. C-5 migration can occur when the C-3 migration product possesses ring strain, but it does not usually compete with C-3 migration. The greater preference for C-3 migration is due to the carbonyl oxygen atom, which greatly stabilizes the intermediate. Studies of the photochemical rearrangement of N-mesyloxylactams showed that the lone pair of the carbonyl oxygen atom, and not the degree of the substitution atthe migrating carbon atoms, is the governing factor in the regioselectivity of the reaction. Copyright
- Pichette, Simon,Aubert-Nicol, Samuel,Lessard, Jean,Spino, Claude
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supporting information; experimental part
p. 1328 - 1335
(2012/04/05)
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- Atom-transfer cyclization with CuSO4/KBH4: A formal "activators generated by electron transfer" process also applicable to atom-transfer polymerization
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The 4-exo and 5-exo-trig atom-transfer cyclizations of 1, 8a-e, 9, 12, and 13 can be mediated with as little as 0.05 mol % of Cu(TPMA)SO 4?5H2O in the presence of 2.5 mol % of borohydride salts in 10 min at room temperature in air. This formal "activators generated by electron transfer" (AGET) procedure utilizes a cheap and oxidatively stable copper source (CuSO4?5H2O) and can be carried out in environmentally benign solvents (EtOH). It is possible to alter the product distribution in the 5-endo radical-polar crossover reactions of 10a,b and 11 by tailoring the amount of borohydride. Cyclization onto alkynes 14 and 15 is also possible in only 20 min. Controlled radical polymerization of styrene, with increased rates over conventional atom-transfer radical polymerization (ATRP), can be carried out in a controlled fashion (Mn, PDI) using either CuBr or CuSO4?5H2O and Bu 4NBH4.
- Clark, Andrew J.,Collis, Alana E. C.,Fox, David J.,Halliwell, Lauren L.,James, Natalie,O'Reilly, Rachel K.,Parekh, Hemal,Ross, Andrew,Sellars, Andrew B.,Willcock, Helen,Wilson, Paul
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experimental part
p. 6778 - 6788
(2012/09/25)
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- Method of synthesis of phosphinic acids based on hypophosphites: VIII.1 synthesis of α-aminoalkylphenethylphosphinic acids
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Development of methodology of double Arbuzov rearrangement based on hypophosphites allows a one-pot formation of two unsymmetrical phosphorus-carbon bonds by the Michael-Pudovik type reaction of stepwise addition of the intermediately forming silyl esters of trivalent phosphorus to different unsaturated compounds. A procedure was developed of the synthesis of α-aminoalkylphenethylphosphinic acids. Bis-(trimethylsilyl) phenethylphosphonite formed as a result of the addition of bis(trimethylsilyl) hypophosphite to styrene in situ was added without isolation from the reaction mixture to Schiff bases obtained preliminary from benzylamine or diphenylmethylamine and various aldehydes. The subsequent removal of N-protecting groups by hydrogenation or acidic hydrolysis gave a number of new α-aminoalkylphenethylphosphinic acids.
- Dmitriev,Ragulin
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experimental part
p. 1786 - 1791
(2012/01/12)
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- Preparation of stereodefined homoallylic amines from the reductive cross-coupling of allylic alcohols with imines
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Regio-, diastereo-, and enantioselective coupling reactions between imines and allylic alcohols have been developed. These coupling reactions deliver complex homoallylic amine products through a convergent C-C bond forming process that does not proceed through intermediate allylic organometallic reagents. In general, convergent coupling, by exposure of an allylic alkoxide to a preformed Ti-imine complex, occurs with allylic transposition in a predictable and stereocontrolled manner. While simple diastereoselection in these reactions is high, delivering anti-products with ≥20:1 selectivity, the organometallic transformation described is compatible with a diverse range of functionality and substrates (including aliphatic and aromatic imines, allylic silanes, trisubstituted alkenes, vinyl- and aryl halides, trifluoromethyl groups, thioethers, and aromatic heterocycles). Alkene geometry of the products is a complex function of the allylic alcohol structure and is consistent with a mechanistic proposal based on syn-carbometalation followed by syn-elimination by way of a boat-like transition state geometry. Single asymmetric coupling reactions provide a means to translate the stereochemical information of the allylic alcohol to the homoallylic amine or to control diastereoselection in the coupling reactions of achiral allylic alcohols with chiral imines. Double asymmetric coupling reactions are also described that afford a unique means to control stereoselection in these complex convergent coupling processes. Finally, empirical models are proposed that are consistent with the observed stereochemical course of these coupling reactions en route to chiral homoallylic amines possessing di- or trisubstituted alkenes and anti- or syn- relative stereochemistry at the allylic and homoallylic positions.
- Chen, Ming Z.,McLaughlin, Martin,Takahashi, Masayuki,Tarselli, Michael A.,Yang, Dexi,Umemura, Shuhei,Micalizio, Glenn C.
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supporting information; experimental part
p. 8048 - 8059
(2011/02/26)
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- Preparation of dialkyl 1-(Alkylamino)alkylphosphonates, alkyl [1-(Alkylamino)alkyl]phenylphosphinates and [1-(Alkylamino)alkyl] diphenylphosphine oxides via in situ generated iminium ions
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The reaction of trialkyl phosphites, dialkyl phenylphosphonites or alkyl diphenylphosphinites with N-alkylalkanimines in the presence of hydrogen chloride gives dialkyl 1-(alkylamino)alkylphosphonates, alkyl amino)alkyl]phenylphosphinates or [1-(alkylamino)alkyl]diphenylphosphine oxides respectively, via Arbusov-like reaction of iminium salts generated in situ from N-alkylalkanimines. This reaction is an alternative and competitive to known method of preparation based on the addition of H-P compounds to N-alkylalkanimines, because it gives higher yields, no heating is necessary, and the isolation of products is easy. Georg Thieme Verlag Stuttgart · New York.
- Goldeman, Waldemar,Soroka, Miroslaw
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experimental part
p. 2437 - 2445
(2010/09/04)
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- Rapid synthesis of carbohydrate derivatives, including mimetics of C-linked disaccharides and C-linked aza disaccharides, using the hetero-Diels-Alder reaction
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In this work we demonstrate the value of performing a hetero-Diels-Alder reaction (HDAR) between Danishefsky's diene and a range of aldehydes or imines, under microwave irradiation. By using a range of aldehydes and imines, including those derived from carbohydrates, access to functionalized 2,3-dihydro-4H- pyran-4-ones or 2,3-dihydro-4-pyridinones in good to excellent synthetic yields is possible. A particular strength of the methodology is its ability to access mimetics of C-linked disaccharides and C-linked aza disaccharides, targets of current therapeutic interest, in a rapid, convenient, and diastereoselective manner. The effect of high pressure on the HDARs involving carbohydrate-derived aldehydes and imines is also explored, with enhancement in yields occurring for the aldehyde substrates. Finally, HDARs using carbohydrate derived ketones, enones, and enals are described under a range of conditions. Optimum results were obtained under high-pressure conditions, with highly functionalized carbohydrate derivatives being afforded, in good yields, in this way.
- Burland, Peter A.,Coisson, David,Osborn, Helen M. I.
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supporting information; experimental part
p. 7210 - 7218
(2011/02/22)
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- Multicomponent reactions of convertible isonitriles
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(Chemical Equation Presented) A new family of unsaturated isonitriles has been prepared by the base-promoted ring-opening of oxazoles, offering an alternative to the conventional formamide dehydration route. These compounds undergo the full complement of multicomponent reactions for which isonitriles are known and offer the desirable trait of giving amide products that readily participate in acyl substitution reactions (hence, they are convertible). Moreover, they do not have the objectionable odors for which isonitriles are typically known, making them more accessible as reagents for organic synthesis. One focus of the work is isonitriles bearing perfluorinated alkyl groups that enable the ready separation of such reagents from nonfluorinated reaction products using the "light" fluorous method of fluorous solid-phase extraction.
- Pirrung, Michael C.,Ghorai, Subir,Ibarra-Rivera, Tannya R.
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experimental part
p. 4110 - 4117
(2009/09/25)
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- Nitrile biotransformations for the synthesis of highly enantioenriched β-hydroxy and β-amino acid and amide derivatives: A general and simple but powerful and efficient benzyl protection strategy to increase enantioselectivity of the amidase
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(Chemical Equation Presented) Biotransformations of a number of racemic β-hydroxy and β-amino nitrile derivatives were studied using Rhodococcus erythropolis AJ270, the nitrile hydratase and amidase-containing microbial whole cell catalyst, under very mild conditions. The overall enantioselectivity of nitrile biotransformations was governed predominantly by the amidase whose enantioselectivity was switched on remarkably by an O- and a N-benzyl protection group of the substrates. While biotransformations of β-hydroxy and β-amino alkanenitriles gave low yields of amide and acid products of very low enantiomeric purity, introduction of a simple benzyl protection group on the β-hydroxy and β-amino of nitrile substrates led to the formation of highly enantioenriched β-benzyloxy and β-benzylamino amides and acids in almost quantitative yield. The easy protection and deprotection operations, high chemical yield, and excellent enantioselectivity render the nitrile biotransformation a useful protocol in the synthesis of enantiopure β-hydroxy and β-amino acids.
- Ma, Da-You,Wang, De-Xian,Pan, Jie,Huang, Zhi-Tang,Wang, Mei-Xiang
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p. 4087 - 4091
(2008/09/20)
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- Generation of molecular diversity using a complexity-generating MCR-platform towards triazinane diones
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Triazinane diones, readily generated by a recently reported multicomponent reaction, can be easily alkylated with various alkyl halides, allowing a wide variety of complexity-generating secondary reactions. Because of the high variability of the initial multicomponent reactions and the multiple possibilities for participation of substituents in the secondary reactions, a highly diverse set of complex products was obtained in short and efficient reaction sequences.
- Groenendaal, Bas,Ruijter, Eelco,De Kanter, Frans J. J.,Lutz, Martin,Spek, Anthony L.,Orru, Romano V. A.
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experimental part
p. 3158 - 3165
(2009/02/03)
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- A stable, convertible isonitrile as a formic acid carbanion [ -COOH] equivalent and its application in multicomponent reactions
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The application of 2-(2,2-dimethoxyethyl) phenyl isonitrile in Ugi, Passerini, and Ugi-Smiles reactions is described. The simple transformation to highly activated indolyl amides allows functional-group conversion of the isonitrile moiety into a variety of carboxylic acid derivatives, overall acting as a neutral, nucleophilic COOH equivalent. Georg Thieme Verlag Stuttgart.
- Kreye, Oliver,Westermann, Bernhard,Wessjohann, Ludger A.
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p. 3188 - 3192
(2008/09/20)
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- Versatile, fragrant, convertible isonitriles
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The metalation of oxazoles leads to ring opening to the isocyanoenolate that can be O-acylated to give the unsaturated isonitriles. These substances undergo conventional multicomponent reactions. The products of their reactions are readily converted to acyl substitution products by treatment with acid and a nucleophile. These unsaturated isonitriles are notable by their simple preparations and, unusually, their nonoffensive odors. Copyright
- Pirrung, Michael C.,Ghorai, Subir
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p. 11772 - 11773
(2007/10/03)
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- Catalytic imino Diels-Alder reaction by triflic imide and its application to one-pot synthesis from three components
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An imino Diels-Alder reaction of 2-siloxydienes with aldimines catalyzed by triflic imide (Tf2NH; 0.1~10 mol % amount) has been developed leading to substituted piperidin-4-ones. Tf2NH catalyst is compatible with basic functions, such as pyridine and indole rings in the imino Diels-Alder reaction. Furthermore, X-ray crystallographic analysis indicates that trans-2,6-diphenyl-4-piperidinone 4a obtained by this reaction has a unique conformation in the solid state.
- Takasu, Kiyosei,Shindoh, Naoya,Tokuyama, Hidetoshi,Ihara, Masataka
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p. 11900 - 11907
(2007/10/03)
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- Diastereochemical diversity of imidazoline scaffolds via substrate controlled TMSCI mediated cycloaddition of azlactones
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(Chemical Equation Presented) We report herein a trimethylsilyl chloride mediated substrate controlled 1,3-dipolar cycloaddition for the diastereoselective synthesis of either syn- or anti-imidazolines. This method provides scaffolds with four points of diversity and control over two stereocenters.
- Sharma, Vasudha,Tepe, Jetze J.
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p. 5091 - 5094
(2007/10/03)
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- Base induced carbon-nitrogen (C=N) double bond migration in Schiff bases
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Various Schiff bases have been prepared to study base induced carbon-nitrogen double bond migrations. Schiff bases derived from aliphatic aldehydes display highest selectivity. Hydrolysis of the resulting rearranged Schiff base provides an entry to make amines from aldehydes. The reaction has possible practical application.
- Gangadasu,Narender,China Raju,Jayathirtha Rao
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p. 2598 - 2600
(2007/10/03)
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- A straightforward approach towards thiazoles and endothiopeptides via Ugi reaction
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Endothiopeptides can easily be obtained via Ugi reaction using thio acids as acid components. If isonitriles with an acetal group are applied, the endothiopeptides can directly be converted into thiazoles using TMSCl-NaI under microwave irradiation. The Royal Society of Chemistry 2005.
- Kazmaier, Uli,Ackermann, Stefanie
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p. 3184 - 3187
(2007/10/03)
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- One-pot synthesis of N-chloroacetyl 1-aminoalkyl phosphonates - Precursors of 4-phosphono-β-lactams
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4-Phosphono-β-lactams are synthesized via a three-step sequence, including final formation of the C3-C4 bond through a phosphorus-stabilized carbanion. The chlorinated precursors can be synthesized via two different methods: a one-pot N-acylation of an aromatic imine followed by addition of a trialkyl phosphite or phosphonylation of a suitable imine followed by N-acylation in a separate reaction step. The former method was preferred because of the ease of the reaction and the good yields obtained. Georg Thieme Verlag Stuttgart.
- Moonen, Kristof,Stevens, Christian V.
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p. 3603 - 3612
(2007/10/03)
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- Thiourea-Catalyzed Enantioselective Hydrophosphonylation of Imines: Practical Access to Enantiomerically Enriched α-Amino Phosphonic Acids
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Chiral thiourea 1b catalyzes the highly enantioselective hydrophosphonylation of a wide range of N-benzyl imines. The hydrophosphonylation products are readily deprotected by hydrogenolysis, providing access to free α-amino phosphonic acids in highly enantioenriched form. Copyright
- Joly, Guy D.,Jacobsen, Eric N.
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p. 4102 - 4103
(2007/10/03)
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- Aldehyde addition to allylic stannanes via a transmetallation pathway: Stereocontrol in the absence of internal coordination
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Methyltin trichloride and indium(III) chloride promote the addition of aldehydes to cyclic allylic stannanes providing good yields of the corresponding homoallylic alcohols. These reactions proceed via an initial transmetallation involving anti approach of the electrophile, followed by syn aldehyde addition that is erythro selective. These Lewis acids do not promote the corresponding addition of imines, rather providing the same homoallylic alcohols after an in situ aqueous hydrolysis. Imine addition is possible with boron trifluoride-diethyl ether as the Lewis acid.
- Marshall, Raymond L.,Muderawan, I. Wayan,Young, David J.
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p. 957 - 962
(2007/10/03)
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- A versatile multi-component one-pot thiazole synthesis
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A new multi-component reaction (MCR) of oxo components, primary amines, thiocarboxylic acids and a special isocyanide yielding 2,4-disubstituted thiazoles is described. This one-pot, one-step reaction is an alternative to current methods of thiazole ring formation and can be applied to combinatorial chemistry as well as in the total synthesis of thiazole containing natural products.
- Heck, Stefan,D?mling, Alexander
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p. 424 - 426
(2007/10/03)
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- β- and γ-lactams by nickel powder mediated 4-exo or 5-endo radical cyclisations. A concise construction of the mesembrine skeleton
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N-Alkenyl trichloroacetamides, upon treatment with nickel powder and acetic acid in refluxing 2-propanol undergo reversible 4-exo radical cyclisation. The cyclised radical can be trapped in different ways leading to β-lactams. When the trap is omitted or not efficient enough, unusual irreversible 5-endo cyclisation occurs affording functionalised five-membered lactams. Synthesis of bicyclic γ-lactams has also been examined providing in few steps an access to the Sceletium alkaloids skeleton.
- Cassayre, Jerome,Quiclet-Sire, Beatrice,Saunier, Jean-Baptiste,Zard, Samir Z.
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p. 1029 - 1040
(2007/10/03)
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- N,Se-Acetals: Preparation and Use in Diastereoselective Radical Reactions
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A new facile synthesis of N,S- and N,Se-acetals starting from aldehydes and primary amines is presented (Schemes 3-5). These acetals are used as precursors for stereoselective radical deuteration and allylation reactions (Schemes 6 and 7, Tables 1 and 2). The stereochemical outcome of the reactions depends on the radical trap and the substituents at the N-atom. Deuterations give always anti products with moderate to high selectivities. The allylation reactions give either syn or anti products with low to moderate selectivities. The observed stereoselectivities can be explained with a model based on minimization of A1,3 strain and are controlled by steric and stereoelectronic effects.
- Stojanovic, Aleksandar,Renaud, Philippe
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p. 353 - 373
(2007/10/03)
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- N,Se-acetals: Easy preparation and application to radical mediated EPC synthesis
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A facile synthesis of N,S- and N,Se-acetals starting from aldehydes and primary amines is presented. These acetals are used as precursors for radical reactions. The stereoselectivity of the reactions depends on the radical trap used.
- Stojanovic, Aleksandar,Renaud, Philippe
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p. 9199 - 9202
(2007/10/03)
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- The Addition of γ-(Trimethylsilyl)allylboronates to Imines
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The addition of γ-(trimethylsilyl)allylboronates to imines is described and compared with the addition of simple allylboronates to imines.The addition of γ-(trimethylsilyl)allylboronates is found to be more efficient than the addition of simple allylboronates to imines.The stereoselectivity is dependant upon the nature of the imine; imines derived from aromatic aldehydes give anti products and imines derived from aliphatic aldehydes give syn products.Proof of stereochemistry was established by conversion of the anti and syn derivatives to their respective Z- and E-dienes by a methylation/E-2 elimination process.With α-alkoxy aldehydes the reaction proceeds with excellent selectivity giving the product of Felkin-Ahn addition.
- Wuts, Peter G. M.,Jung, Yong-Woon
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p. 365 - 372
(2007/10/02)
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- Synthesis of organophosphorus compounds via silyl esters of phosphorous acids
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The addition of trimethylsilyloxy phosphorus (III)derivatives generated in situ to imines at room temperature provides a mild selective and high yielding route to α-aminoalkylphosphorate and α-aminoalkylphenylphosphinate esters. Isocyanates and carbodiimides react similarly to give phosphonoureas and phosphonoguarnidines respectively aldehydes and ketones are much less reactive and cyanides are inert.
- Afarinkia, Kamyar,Rees, Charles W.,Cadogan, John I. G.
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p. 7175 - 7196
(2007/10/02)
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- 1-(Triphenylphosphorylideneaminomethyl)benzotriazole (BETMIP) a Novel +CH2N= Synthetic Equivalent: Its Application to the Synthesis of Carbodiimides, Imines, Isothiocyanates, Aziridines, and Secondary Amines
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One-carbon homologation has been achieved in novel syntheses of the title compounds by one-pot reaction of 1-(triphenylphosphorylideneaminomethyl)benzotriazole (1) with Grignard reagents followed by in situ transformations of the phosphorazene functionality with isocyanates, aldehydes, carbon disulfide, ethylene oxide, and alkyl halides, respectively.
- Katritzky, Alan R.,Jiang, Jinglong,Urogdi, Laszlo
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p. 565 - 567
(2007/10/02)
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- Photochemical Reactivity of Aldimines from 2,2-Dimethyl-3-oxo-3-phenylpropanal
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The syntheses of some thermally labile aldimines of 2,2-dimethyl-3-oxo-3-phenylpropanal are described.The aldimines (7a-c) are photochemically reactive and undergo fission mainly into isopropyl phenyl ketone.Several other minor products are also formed.On
- Armesto, Diego,Ramos, Ana,Perez-Ossorio, Rafael,Horspool, William M.
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- A NOVEL RETRO-ENE REACTION THE FRAGMENTATION OF N-BENZYL-2-BENZOYL-2-METHYLPROPANIMINE
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N-benzyl-2-benzoyl-2-methylpropanimine treated with nucleophiles undergoes a fragmentation reaction that can be envisaged as a retro-ene reaction via the formation of an intermediate hemiketal.
- Armesto, Diego,Ramos, Ana,Perez-Ossorio, Rafael
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p. 5195 - 5198
(2007/10/02)
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- α-Amino-phosphonous acids for inhibiting bacteria and yeast
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The present invention relates to new phosphonous acid derivatives, especially to α-amino-phosphonous acids and processes for their production. The new phosphonous acids are valuable chemotherapeutica in the treatment of pathogenic bacteria, gram-negative
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