- Photoinduced Palladium-Catalyzed Dicarbofunctionalization of Terminal Alkynes
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Herein, a conceptually distinct approach was developed that allowed for the dicarbofunctionalization of alkynes at room temperature using simple, bench-stable alkyl iodides and a second molecule of alkyne as coupling partner. Specifically, the photochemical activation of palladium complexes enabled this strategic dicarbofunctionalization via addition of alkyl radicals from secondary and tertiary alkyl iodides and formation of an intermediate palladium vinyl complex that could undergo subsequent Sonogashira reaction with a second alkyne molecule. This alkylation–alkynylation sequence allowed the one-step synthesis of 1,3-enynes including heteroarenes and biologically active compounds with high efficiency without exogenous photosensitizers or oxidants and now opens up pathways towards cascade reactions via photochemical palladium catalysis.
- Yang, Zhen,Koenigs, Rene M.
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supporting information
p. 3694 - 3699
(2021/02/01)
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- Visible-light-mediated multicomponent reaction for secondary amine synthesis
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The widespread presence of secondary amines in agrochemicals, pharmaceuticals, natural products, and small-molecule biological probes has inspired efforts to streamline the synthesis of molecules with this functional group. Herein, we report an operationally simple, mild protocol for the synthesis of secondary amines by three-component alkylation reactions of imines (generated in situ by condensation of benzaldehydes and anilines) with unactivated alkyl iodides catalyzed by inexpensive and readily available Mn2(CO)10. This protocol, which is compatible with a wide array of sensitive functional groups and does not require a large excess of the alkylating reagent, is a versatile, flexible tool for the synthesis of secondary amines.
- Wang, Xiaochen,Zhu, Binbing,Dong, Jianyang,Tian, Hao,Liu, Yuxiu,Song, Hongjian,Wang, Qingmin
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supporting information
p. 5028 - 5031
(2021/05/28)
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- A mild and highly chemoselective iodination of alcohol using polymer supported DMAP
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The synthesis of organic compounds using polymer supported catalysts and reagents, where the required product is always in solution, has been of great interest in recent years, both in industries and academia especially in pharmaceutical research. Here, a simple and efficient method for conversion of alcohols into their iodides in high yield using polymer supported 4-(Dimethylamino)pyridine (DMAP) is described. Polymer supported DMAP is used in catalytic amount and is recovered and reused several times. Additionally, this method is highly chemoselective. [Figure not available: see fulltext.]
- Das, Diparjun,H Anal, Jasha Momo,Rokhum, Lalthazuala
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p. 1695 - 1701
(2017/03/08)
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- A transition-metal-free Heck-type reaction between alkenes and alkyl iodides enabled by light in water
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A transition-metal-free coupling protocol between various alkenes and non-activated alkyl iodides has been developed by using photoenergy in water for the first time. Under UV irradiation and basic aqueous conditions, various alkenes efficiently couple with a wide range of non-activated alkyl iodides. A tentative mechanism, which involves an atom transfer radical addition process, for the coupling is proposed.
- Liu, Wenbo,Li, Lu,Chen, Zhengwang,Li, Chao-Jun
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supporting information
p. 6170 - 6174
(2015/06/08)
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- Iodination of alcohols over Keggin-type heteropoly compounds: A simple, selective and expedient method for the synthesis of alkyl iodides
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Different catalysts derived from Keggin-type heteropoly compounds were prepared and their catalytic activities have been compared in the iodination of benzyl alcohol with KI under mild reaction conditions. A high catalytic activity was found over tungstophosphoric acid supported on silica and titania. The effect of catalyst loading, iodine source and the nature of substituents on the aromatic ring of benzyl alcohol were investigated. Finally, several competitive reactions were studied between structurally diverse alcohols. This protocol provides a mild and expedient way for the conversion of various alcohols to their corresponding alkyl iodides with high selectivity.
- Rafiee, Ezzat,Mahdavia, Houri,Joshaghani, Mohammad
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experimental part
p. 135 - 140
(2011/06/09)
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- Salts of Mosher's thioacid: agents for determining the enantiomer excess of SN2 substrates
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The racemic and the (S)-enantiomer of Mosher's thioacid, 2-methoxy-2-trifluoromethylphenylacetic thioacid, form air-stable salts with Proton Sponge [1,8-bis(dimethylamino)naphthalene]. These salts are powerful nucleophiles that react cleanly (SN2 inversion) in CDCl3 with optically active alkyl halides ranging in reactivities from unactivated alkyl bromides and iodides to benzylic bromides. The diastereomeric excess (de) of the thioester products indicates the enantiomeric excess (ee) of the starting alkyl halides.
- Richman, Jack E.
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supporting information; experimental part
p. 2793 - 2796
(2010/07/06)
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- Mechanism of decomposition of quasiphosphonium intermediates: Borderline SN1 character of alkyl-oxygen fission in sec-alkyloxyphosphonium salts
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Short-lived alkoxyphosphonium intermediates have been detected in the interactions of alkyl diphenylphosphinites ROPPh2 (R = Et, Pr i, Bu8, and 3-pentyl) with iodomethane at room temperature. Phosphorus chemical shifts for the sec-alkoxy(methyl) diphenylphosphonium iodides (δp 68.6-68.7 ppm) are at slightly higher field than for ethoxy(methyl)diphenylphosphonium iodide (δp 72.4 ppm), in accord with higher electron density at phosphorus in the secondary alkyl sytems. Relative rates of decomposition in CDCl3 (Me > Et > Pri ? neopentyl) are in accord with SN2-type cleavage of the R-O bond but within the secondary alkyl series the relative rates (Pri 8 N1 mechanism is proposed.
- Hudson,Qureshi
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p. 473 - 480
(2007/10/03)
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- Triphenylphosphine/2,3-dichloro-5,6-dicyanobenzoquinone as a new, selective and neutral system for the facile conversion of alcohols, thiols and selenols to alkyl halides in the presence of halide ions
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A mixture of triphenylphosphine (Ph3P) and 2,3-dichloro-5,6-dicyanobenzoquinone in CH2Cl2 affords a complex which in the presence of R4NX (X=Cl, Br, I) converts alcohols, thiols and selenols into their corresponding alkyl halides in high yields at room temperature. The method is highly selective for the conversion of 1° alcohols in the presence of 2° ones and also 1° and 2° alcohols in the presence of 3° alcohols, thiols, epoxides, trimethylsilyl- and tetrahydropyranyl ethers, 1,3 dithianes, disulfides, and amides.
- Iranpoor,Firouzabadi,Aghapour,Vaez zadeh
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p. 8689 - 8693
(2007/10/03)
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- Mild conversion of alcohols to alkyl halides using halide-based ionic liquids at room temperature
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Formula presented Alcohols were efficiently converted to alkyl halides using 1-n-butyl-3-methylylimidazolium halides (ionic liquids) in the presence of Bronsted acids at room temperature. The alkyl halide products were easily isolated from the reaction mixture via simple decantation or extraction, and the 1-n-butyl-3-methylimidazolium cation could be recycled for further uses.
- Ren, Rex X.,Wu, Jeff Xin
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p. 3727 - 3728
(2007/10/03)
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- The first efficient iodination of unactivated aliphatic hydrocarbons
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No heavy metals, no enzymes, and a simple protocol: the direct iodination of aliphatic hydrocarbons, which has not been possible to date, can now be carried out in multiphase systems [see for example Eq. (l)]. In situ generated tetraiodomethane serves as a key intermediate in this selective radical chain reaction initiated by a single electron transfer. This room-temperature, efficient transformation is highly regioselective, easy to work-up, and hence widely applicable.
- Schreiner, Peter R.,Lauenstein, Oliver,Butova, Ekaterina D.,Fokin, Andrey A.
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p. 2786 - 2788
(2007/10/03)
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- Activation of the silicon-halogen bond by bismuth (III) halides. Halogenation of alcohols: prospective and mechanism
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In the presence of catalytic amount of BiCl3, chloromethylsylanes can be used as chlorinating agents for alcohols, and as chloro-dealkylating agents for silyl ethers and carboxylic and sulfonic esters.The chlorination of (R)-(-)-octan-2-ol and the (R)-(-)-2-mesyloctane by TMSCl gave predominantly the (S)-(+)-2-chlorooctane with inversion of configuration at secondary carbon.According to the class of alcohol, the mechanism involves SN2, SN2' or SN1 processes.This new activation of the Si-Cl bond, probably trough a Si-Cl...BiCl3 interaction gives a hard-soft reagent that can generate a silicenium cation, was also observed with Me3SiBr, BiBr3 and Me3SiI, BiI3 systems.The reaction is also presented as a possible alcoholysis of chlorosilanes, which can lead to siloxanes in non-aqueous conditions. catalysis / halogenation / alcohol / ester / silyl ether / chlorosilane / chlorotrimethylsilane / bromotrimethylsilane / iodotrimethylsilane / siloxane / bismuth (III) halide
- Labrouillere, Mireille,Roux, Christophe Le,Oussaid, Abdelouahad,Gaspard-Iloughmane, Hafida,Dubac, Jacques
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p. 522 - 530
(2007/10/02)
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- Development and Application of a Continuous Microwave Reactor for Organic Synthesis
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A laboratory-scale continuous microwave reactor (CMR) has been developed and used to conduct organic syntheses routinely, rapidly, and safely in a range of solvents, under pressures up to 1400 kPa and at temperatures up to 200 deg C.Advantages and applications of the CMR are discussed, along with the rationale for the design.Reactions carried out with the CMR included nucleophilic substitution, addition, esterification, transesterification, acetalization, amidation, base- and acid-catalyzed hydrolysis, isomerization, decarboxylation, and elimination.Name reactions included the Michael addition, Hofmann degradation, Williamson ether synthesis, and the Mannich, Finkelstein, Baylis-Hillman, and Knoevenagel reactions.
- Cablewski, Teresa,Faux, Alan F.,Strauss, Christopher R.
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p. 3408 - 3412
(2007/10/02)
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- ORGANOBORANES FOR SYNTHESIS.9. RAPID REACTION OF ORGANOBORANES WITH IODINE UNDER THE INFLUENCE OF BASE. A CONVENIENT PROCEDURE FOR THE CONVERSION OF ALKENES INTO IODIDES VIA HYDROBORATION
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The reaction of organoborane with iodine is strongly accelerated by sodium hydroxide.Organoboranes derived from terminal alkenes react with the utilization of approximately two of the three alkyl groups attached to boron, providing a maximum of 67percent yield of alkyl iodide.Thus, hydroboration-iodination of 1-decene gives a 60percent yield of n-decyl iodide.Secondary alkyl groups, derived from internal alkenes, react more sluggishly and only one of the three alkyl groups attached to boron is converted to the iodide.Thus, the procedure applied to 2-butene provides a 30percent yield of 2-butyl iodide.The use of disiamylborane bis-(3-methyl-2-butylborane, Sia2BH as hydroborating agent increases the yield of iodides from terminal alkenes since the primary alkyl groups react in preference to the secondary siamyl groups.Consequently, hydroboration of 1-decene with Sia2BH, followed by iodination gives a 95percent yield of n-decyl iodide.The use of methanolic sodium methoxide in place of sodium hydroxide provides alkyl iodides in considerably higher yields.The combination of hydroboration with iodination in the presence of a base provides a convenient method for the anti-Markovnikov hydroiodination of alkenes.The base-induced iodination of organoboranes proceeds with the inversion of configuration at the reaction center, as shown by the formation of endo-2-iodonorbornane from tri-exo-norbornylborane.
- Brown, Herbert C.,Rathke, Michael W.,Rogic, Milorad M.,de Lue, Norman R.
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p. 2751 - 2762
(2007/10/02)
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- Radical Cations from Alkyl Iodides in Aqueous Solution
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Radical cations RI(1+) and (RIIR)(1+) are generated upon OH radical-induced oxidation of alkyl iodides in acidic (pHOH-adduct.Although alkyl iodide radical cations have been reported to exist in a solid, low-temperature matrix, they have so far not been detected in the liquid, particularly the aqueous phase.Both radical cations establish an equilibrium: .For R=Me the stability constant of the 2?-1?* three-electron-bonded species has been estimated to K>/=5E4 mol-1dm3. (RIIR)(1+) exhibits a strong optical absorption band in the visible; λmax is red-shifted with increasing electron-releasing power of R and ranges from 4115 nm (R=Me) to 470 nm (R=s-C4H9).The molecular radical cation absorbs in a comparatively much narrower range from 310-320 nm.It is suggested that it exists as (RIOH2)(1+), i.e. as an associate with one water molecule.The alkyl iodide radical cations are strong oxidants. (MeIIMe)(1+), for example, oxidizes I(1-) and Me2S with rate constant values of 7.7E9 mol-1dm3s-1 and 3.6E9 mol-1dm3s-1, respectively.
- Mohan, Hari,Asmus, Klaus-Dieter
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p. 1795 - 1800
(2007/10/02)
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- New Reagents, XXXVII - (α-Lithioalkyl)diphenylarsane Oxides: Synthesis and Application for the Indirect Nucleophilic Haloalkylation
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Due to ready accessibility and high nucleophilicity (α-lithioalkyl)diphenylarsane oxides (2) are favorable reagents for the synthesis of many organoarsenic compounds.In organic synthesis they are recommendable as reagents for indirect nucleophilic haloalkylation reactions (Hal = Cl, Br, I).
- Kauffmann, Thomas,Joussen, Rolf,Woltermann, Annegret
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p. 2135 - 2142
(2007/10/02)
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- Chemical process
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Novel bis(3',5'-mono or dihydrocarbyl-4'-hydroxybenzyl)-1,3-diketones are prepared by reacting a (3',5'-mono or dihydrocarbyl-4'-hydroxybenzyl)-1,3-diketone with an N,N-dihydrocarbyl-2,6-mono or dihydrocarbyl-4-aminomethylphenol and an alkyl halide in the presence of an alkaline earth metal halide. The products are useful as antioxidants.
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- Hydroxyvitamin D2 compounds and process for preparing same
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This invention relates to hydroxylated derivatives of vitamin D2, to processes for preparing such compounds, to intermediates utilized in such processes and to certain isotopically labelled vitamin D2 compounds. The vitamin D2 derivatives would find application in the treatment of or prophylaxsis for various disease states characterized by calcium and phosphorous imbalances and as a substitute for vitamin D3 and its metabolites in their various applications.
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- Chemical process for preparing 1,3-diketones
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Novel (3',5'-dihydrocarbyl-4'-hydroxybenzyl)-1,3-diketones are prepared by reacting an N,N-dihydrocarbyl-2,6-dihydrocarbyl-4-aminomethylphenol with a 1,3-diketone and an alkyl halide in the presence of an alkali or an alkaline earth metal hydride. The products are useful as antioxidants.
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- Chemical process
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Novel 2,4-dihydrocarbylspiro[5.5]undeca-1,4,8-trien-3-one compounds are prepared by reacting an N,N-dihydrocarbyl,2,6-dihydrocarbyl-4-aminomethylphenol with a conjugated diene and an alkyl halide in a liquid solvent medium.
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- ON THE STRUCTURE OF tert-BUTYL HYPOIODITE.
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A compound known as 'tert-butyl hypoiodite' has hitherto been referred to in the literature as a reagent with some synthetic utility. Three methods of preparation have been used to make this material: the reaction of tert-butyl hypochlorite with iodine, the reaction of tert-butyl hypochlorite with metal iodides, and the reaction of potassium tert-butoxide with iodine. Physical and chemical evidence is offered to show that the reagent obtained from the first of these methods is different from that made from the latter two methods. Reaction schemes are proposed to account for the different properties and reactivities of the two reagents. Structures are proposed for the two reagents which rationalize both the physical and chemical properties of the two materials.
- Tanner,Gidley,Das,Rowe,Potter
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p. 5261 - 5267
(2007/10/02)
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- STEREOSPECIFIC SYNTHESIS OF (Z)-13-HEXADECEN-11-YN-1-YL ACETATE THE SEX PHEROMONE OF THE PROCESSIONARY MOTH, AND OF (5Z,7E)-5,7-DODECADIEN-1-OL, A SEX PHEROMONE COMPONENT OF THE FOREST TENT CATERPILLAR
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(Z)-13-hexadecen-11-yn-1-yl acetate (2), the sex pheromone of Thaumetopoea pytyocampa, and (5Z,7E)-5,7-dodecadien-1-ol (3), sex pheromone component of Malacosoma disstria, have been prepared in high chemical and stereoisomeric purity by synthetic schemes involving the stereospecific coupling of ω-functionalized 1-alkynes with (Z)- or (E)-1-iodo-1-alkenes in the presence of a catalytic amount of (PPh3)4Pd and CuI, under phase transfer conditions.
- Rossi, Renzo,Carpita, Adriano
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p. 287 - 290
(2007/10/02)
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- Heats of Formation of Some Simple Alkyl Radicals
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Equilibrium constants, K, for the system Me + RI MeI + R were measured in solution by using electron paramagnetic resonance spectroscopy.Given the entropies of the components of the equilibrium and the heats of formation of the iodides, the relative heats of formation of the alkyl radicals were obtained.With δHf,300(Me) = 34.4 kcal mol-1 chosen as a standard, the following heats of formation for other alkyl radicals were obtained: Et, 28.0; n-Pr, 22.8; i-Pr, 19.2; s-Bu, 13.9; c-C5H9, 25.1; t-Bu, 9.4 kcal mol-1.These data lead to the following C-H bond dissotiation energies for simple alkanes: primary C-H, ca. 100; secondary C-H, ca. 96; tertiary C-H, ca. 94 kcal mol-1.
- Castelhano, A. L.,Griller, D.
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p. 3655 - 3659
(2007/10/02)
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- Addition of Free Radicals to Unsaturated Systems. Part 23. Photochemical and Thermal Reactions of Trifluoroiodomethane with But-2-ene and But-1-ene
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Photochemically-initiated addition of trifluoroiodomethane to but-2-ene gives as the major product the 1:1 adduct 2-iodo-3-trifluoromethylbutane as a mixture of the erythro- and threo-isomers together with compounds formed via dehydroiodination of the 1:1 adduct.Reduction of the 1:1 adduct to 2-trifluoromethylbutane is a major process when the reaction tube is shaken.Under thermal conditions fewer products arising via dehydroiodination of the 1:1 adduct are detected, but products formed via isomerisation of the reactant olefin to but-1-ene are present in low yield.With but- 1-ene initial bidirectional CF3 radical attack takes place to give the 1:1 adducts 1,1,1-trifluoro-3-iodopentane and 1-iodo-2-trifluoromethylbutane in the ratio ca. 19:1.Products are also formed via isomerisation of the reactant olefin and via dehydroiodination of the 1:1 adducts.
- Davies, Terry,Haszeldine, Robert N.,Tipping, Anthony E.
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p. 927 - 932
(2007/10/02)
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