- MeLi + LiCl in THF: One Heterodimer and no tetramers
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The structure of the aggregates formed when mixing methyllithium and lithium chloride in THF has been studied by multinuclear magnetic resonance at 170 K. The data suggest that only one new entity is observed, that is the dimer [(MeLi)(LiCl)], in equilibrium (K ≈ 0.6) with [MeLi]4 and [LiCl]2. NMR diffusion measurements lead to the conclusion that this dimer is trisolvated in THF at 170 K, a solvation scheme in agreement with DFT computations.
- Lecachey, Baptiste,Oulyadi, Hassan,Lameiras, Pedro,Harrison-Marchand, Anne,Gerard, Helene,Maddaluno, Jacques
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Read Online
- Reaction of Halide Ion with 2-(Phenylthio)ethyl Halides in Acetone
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2-(Phenylthio)ethyl chloride specifically deuterated α to the sulfur atom (i.e. 2-Cl) was employed to study the mechanism of displacement of chloride ion by iodide ion in dry acetone solution.Experimental evidence including rate studies has been accumulated that allows the conclusion to be drawn that iodide ion displaces chloride ion from 2-Cl by a classical SN2 mechanism to give 2-I.Under the reaction conditions, however, 2-I is reactive toward anchimerically-assisted ionization which leads to product with the deuterium label scrambled.Reaction of 2-Cl with bromide ion follows a similar course.Our displacement reactions of halide ions by halide ions showed the expected nucleophilicity order of Cl(1-) > Br(1-) > I(1-) and the normal leaving group order of I(1-) > Br(1-) > Cl(1-).An interesting counterion effect was noted with iodides displacing chloride ion.While potassium iodide in acetone converted 2-Cl to the mixture of iodides 2-I and 3-I, tetrabutylammonium iodide caused conversion but the products reverted completely back to the label-scrambled chlorides.The difference in these results is probably because of differences in the thermodynamics of the two systems.
- McManus, Samuel P.,Karaman, Rashid M.,Sedaghat-Herati, Reza,Harris, J. Milton
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Read Online
- 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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- Visible-Light-Mediated C-I Difluoroallylation with an α-Aminoalkyl Radical as a Mediator
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Herein, we report a protocol for direct visible-light-mediated C-I difluoroallylation reactions of α-trifluoromethyl arylalkenes with alkyl iodides at room temperature with an α-aminoalkyl radical as a mediator. The protocol permits efficient functionalization of various α-trifluoromethyl arylalkenes with cyclic and acyclic primary, secondary, and tertiary alkyl iodides and is scalable to the gram level. This mild protocol uses an inexpensive mediator and is suitable for late-stage functionalization of complex natural products and drugs.
- Yue, Fuyang,Dong, Jianyang,Liu, Yuxiu,Wang, Qingmin
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supporting information
p. 7306 - 7310
(2021/10/01)
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- Scalable and Phosphine-Free Conversion of Alcohols to Carbon-Heteroatom Bonds through the Blue Light-Promoted Iodination Reaction
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One of the fundamental and highly valuable transformations in organic chemistry is the nucleophilic substitution of alcohols. Traditionally, these reactions require strategies that employ stoichiometric hazardous reagents and are associated with difficulty in purification of the by-products. To overcome these challenges, here, we report a simple route toward the diverse conversion of alcohols via an SN2 pathway, in which blue light-promoted iodination is used to form alkyl iodide intermediates from simple unreactive alcohols. The scope of the process tolerates a range of nucleophiles to construct C-N, C-O, C-S, and C-C bonds. Furthermore, we also demonstrate that this method can be used for the preparation and late-stage functionalization of pharmaceuticals, as highlighted by the syntheses of thiocarlide, butoxycaine, and pramoxine.
- Liu, Bin,Elder, W. Zachary,Miyake, Garret M.
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p. 3717 - 3727
(2020/03/04)
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- Halogen-Imparted Reactivity in Lithium Carbenoid Mediated Homologations of Imine Surrogates: Direct Assembly of bis-Trifluoromethyl-β-Diketiminates and the Dual Role of LiCH2I
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The selective formal insertion (homologation) of a carbon unit bridging the two trifluoroacetamidoyl chlorides (TFAICs) units is reported. The tactic is levered on a highly chemoselective homologation–metalation–acyl nucleophilic substitution sequence which precisely enables to assemble novel trifluoromethylated β-diketiminates within a single synthetic operation. Unlike previous homologations conducted with LiCH2Cl furnishing aziridines, herein we exploit the unique capability of iodomethyllithium to act contemporaneously as a C1 source (homologating effect) and metalating agent. The mechanistic rationale grounded on experimental evidences supports the hypothesized proposal and, the structural analysis gathers key aspects of this class of valuable ligands in catalysis.
- Castoldi, Laura,Holzer, Wolfgang,Ielo, Laura,Lombino, Jessica,Pace, Vittorio,Prandi, Cristina,Roller, Alexander,Touqeer, Saad
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supporting information
p. 20852 - 20857
(2020/09/12)
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- Visible-Light-Promoted Remote C-H Functionalization of o-Diazoniaphenyl Alkyl Sulfones
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Visible-light irradiation of ortho-diazoniaphenyl alkyl sulfones in the presence of Ru(bpy)32+ results in remote Csp3-H functionalization. Key mechanistic steps in these processes involve intramolecular hydrogen atom transfer from Csp3-H bonds to aryl radicals to generate alkyl/benzyl radicals. Subsequent polar crossover occurs by single-electron oxidation of the alkyl/benzyl radicals to carbenium ions that then intercept nucleophiles. We have developed remote hydroxylations, etherifications, an amidation, and C-C bond formation processes using this strategy.
- Du, Shaofu,Kimball, Elizabeth Ann,Ragains, Justin R.
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supporting information
p. 5553 - 5556
(2017/10/25)
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- HALIDE-MEDIATED DEALKYLATION OF PHOSPHOTRIESTERS
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In one embodiment, a method includes contacting a phosphotriester and a halogen salt in a polar solvent. In another embodiment, a method for dealkylating tributylphosphate includes contacting tributylphosphate and a halogen salt in a polar solvent.
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Paragraph 0010; 0012; 0051
(2018/02/03)
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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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- Microwave assisted synthesis of spirocyclic pyrrolidines - σ1 receptor ligands with modified benzene-N-distance
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Two series of σ1 ligands with a spiro[[2]benzopyran-1, 3′-pyrrolidine] (3) and a spiro[[2]benzofuran-1,3′-pyrrolidine] (4) framework were synthesized and pharmacologically evaluated. Several reaction steps were considerably improved by microwave irradiation. The σ1 affinity of the spirocyclic ligands correlates nicely with the benzene-N-distance, i.e. 2 1 affinity of both compound classes could be increased with large N-substituents (e.g. 2-phenylethyl, octyl). Nevertheless the benzyl derivative 4a represents the most promising σ1 ligand (Ki = 25 nM) due to its high selectivity against the σ2 subtype (>40-fold), the NMDA receptor and 5-HT6 and 5-HT7 receptors. Moreover, 4a did not inhibit the hERG channel in the heart.
- Jasper, Annemarie,Schepmann, Dirk,Lehmkuhl, Kirstin,Vela, Jose Miguel,Buschmann, Helmut,Holenz, Joerg,Wuensch, Bernhard
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experimental part
p. 327 - 336
(2012/08/13)
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- Reactions of perfluorinated alkenyl-, alkynyl-, alkyltrifluoroborates, and selected hydrocarbon analogues with the halogenating agents Hal2 (Hal = F, Cl, Br), "brF" (BrF3-Br2 1:1), and ICl
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Reactions of [Bu4N][RBF3] [R = CnF 2n+1CF=CF (cis, trans), CF2=CF, CF2=C(CF 3), trans-C4H9CF=CF, trans-C6H 5CF=CF, C4H9CH=CH (cis, trans), CF 3C≡C, and C4H9C≡C] with chlorine, bromine, BrF3 + Br2 (as equivalent of "BrF"), and ICl in solution (CH2Cl2, CHCl3, CF 3CH2CF2CH3) led to 1, 2-addition of halogen and/or replacement of boron by halogen (halodeboration). The reaction of [Bu4N][CF3C≡CBF3] with less than equimolar amounts of diluted fluorine (5 %) in 1, 1, 1, 3, 3-pentafluorobutane (PFB) showed only [Bu4N][CF3CF2CF 2BF3] as fluorine addition product besides extensive fluorodeboration. Suspensions of the insoluble K[CF2=CFBF 3] salt reacted with Cl2 and Br2 in CH 2Cl2 giving preferentially products of halogen addition across the C=C bond. In reactions with ICl iododeboration with formation of CF2=CFI occurred besides 1, 2-addition with formation of [CF 2I-CFClBF3]-. The halodeboration reaction of[Bu4N][trans-C4H9CF=CFBF3] with Br2, "BrF", and ICl, of K[trans-C6H 5CF=CFBF3] with Br2, and of [Bu 4N][trans-C4F9CF=CFBF3] with ICl proceeded stereospecifically. Copyright
- Bardin, Vadim V.,Adonin, Nicolay Yu.,Frohn, Hermann-Josef
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experimental part
p. 565 - 579
(2012/05/20)
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- 1,9-dialkoxyanthracene as a 1O2-sensitive linker
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We developed a 1O2-sensitive linker based on a 9,10-dialkoxyanthracene structure. Its cleavage in the presence of 1O2 is quick and high-yielding. A phosphoramidite containing this fragment was prepared and coupled to a variety of molecular fragments, including nucleosides, fluorescent dyes, and a cholesteryl derivative. On the basis of this building block we prepared a fluorogenic probe for monitoring 1O2 in live mammalian cells and visible-light-activated "caged" oligodeoxyribonucleotides. In particular, the fluorogenic 1O2 probe is a conjugate of 4,7,4′,7′-tetrachlorofluorescein and N,N,N′,N′- tetramethylrhodamine coupled to each other via the 1O 2-sensitive linker. Fluorescence of the dyes in this probe is quenched. In the presence of 1O2, the linker is cleaved with formation of 9,10-anthraquinone and two strongly fluorescent dyes: 4,7,4′,7′-tetrachlorofluorescein and N,N,N′,N′- tetramethylrhodamine derivatives. We observed that the fluorescence of the probe correlates with the amount of 1O2 present in solution. The red-light-activated "caged" oligodeoxyribonucleotides are stable duplexes, which consist of an unmodified strand and a blocker strand. The 1O2-sensitive linker is introduced in the interior of the blocker strand. Upon exposure of the duplex to red light in the presence of In3+(pyropheophorbide-a) chloride, the linker is cleaved with formation of the unstable duplex structure. This product decomposes spontaneously, releasing the unmodified strand, which can bind to the complementary target nucleic acid. This uncaging reaction is high-yielding. In contrast, previously reported visible-light-activated reagents are uncaged inefficiently due to competing reactions of sulfoxide and disulfide formation.
- Arian, Dumitru,Kovbasyuk, Larisa,Mokhir, Andriy
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experimental part
p. 3972 - 3980
(2011/05/09)
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- Synthesis and characterization of novel starburst phase transfer catalyst
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A new phase transfer catalyst, 3,5-bis[(2-methyl-naphthylene-1 -yl)-phenylamino-phenyl]-butyl-(2methoxy-naphthalene-1 -yl)-phenylammonium bromide (BPBPB) has been synthesized, characterized using spectral analysis and its catalytic activity ascertained. Efficiency of BPBPB is studied using etherification of phenol and compared with tetra butyl ammonium bromide (TBAB). O-Alkylation of naphthol, iV-alkylation of indole and halogen substitution reactions are carried out using BPBPB and its efficiency is compared with reported PTCs. BPBPB gives high yield of product, the time for completion of the reaction is short and is required in a very low concentration. Almost 95% of this catalyst is regenerated and reused.
- Mathew, Siji,Divia,Nair, T.D. Radhakrishnan,Haridas, Karickal R.
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scheme or table
p. 1389 - 1393
(2011/01/13)
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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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- Simple synthesis of fresh alkyl iodides using alcohols and hydriodic acid
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A simple synthesis of fresh alkyl iodides using alcohols and hydriodic acid (HI) is reported. The alkyl iodides were obtained in quick and easy work-up with good to excellent yields (66-94%) and very high purities (97-99%). Freshly prepared iodomethane and 1-iodobutane were applied to synthesize biologically relevant 3,7-dimethyladenine and 9-butyladenine, which were characterized thoroughly using 1D and 2D NMR, individually.
- Klein, Suzane M.,Zhang, Cungen,Jiang, Yu Lin
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p. 2638 - 2641
(2008/09/19)
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- Transformation of tertiary amines into alkylating reagents by treatment with 2-chloro-4,6-dimethoxy-1,3,5-triazine. A synthetic application of side-reaction accompanying coupling by means of 4-(4,6-dimethoxy-[1,3,5] triazin-2-yl)-4-methyl-morpholin-4-ium chloride (DMTMM)
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Mild reaction conditions are described for the preparation of a number of alkyl chlorides and 2-dialkyl(aryl)amino-4,6-dirnethoxy-1,3,5-triazines by dealkylation of quaternary triazinylammonium chlorides formed as reactive intermediates in reaction of tertiary amines with 2-chloro-4,6-dimethoxy-1,3,5- triazine. The high selectivity of substitution was observed within the reactivity order of the alkyl groups: benzyl ～ allyl > methyl > n-alkyl. Studies on dealkylation of S-(-)-J-dimethyl-(1-phenylethyl)amine to R-(+)-1-chloro-1-phenylethane revealed that reaction proceeded with an inversion of configuration on the carbon atom as may be expected for SN2 type substitution. The scope of reaction was extended by exchange of anion in quaternary triazinylammonium chlorides with 1-, SCN-, C6H5O-, CH3COO- followed by N-dealkylation step.
- Kolesinska,Kaminski
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experimental part
p. 2115 - 2123
(2009/04/07)
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- Synthesis of selenocystine derivatives from cystine by applying the transformation reaction from disulfides to diselenides
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A stepwise conversion of a disulfide (SS) to a diselenide (SeSe) bond through the corresponding iodide intermediate was implemented and was applied to the synthesis of selenocystamine and l-selenocystine derivatives from cystamine and l-cystine, respectively, in moderate yields.
- Iwaoka, Michio,Haraki, Chie,Ooka, Ryuta,Miyamoto, Masahiro,Sugiyama, Ai,Kohara, Yumiko,Isozumi, Noriyoshi
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p. 3861 - 3863
(2007/10/03)
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- Acyl iodides in organic synthesis: V. Reactions with carboxylic acid esters
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Acyl iodides react with alkyl, alkenyl, and aralkyl esters derived from saturated, unsaturated, and aromatic mono- and dicarboxylic acids in the absence of a catalyst. The reaction involves cleavage of the OR bond and formation of organic iodide RI (including CH2=CHI) and one or two symmetric carboxylic acid anhydrides. Phenyl acetate reacts with benzoyl iodide to give acetyl iodide and phenyl benzoate as a result of cleavage of the (O=)C-O bond. The reaction of diethyl fumarate with acetyl iodide is accompanied by cis- trans isomerization to afford maleic anhydride. In the reactions of acetyl iodide with diethyl oxalate and diethyl malonate, CO and CO2 and CO 2 and polyketene are formed, respectively, in addition to ethyl iodide and acetic anhydride. Ethyl esters of strong organic acids, e.g., ethyl trihaloacetates, failed to react with acyl iodides under analogous conditions.
- Voronkov,Trukhina,Vlasova
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p. 357 - 359
(2007/10/03)
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- Acyl iodides in organic synthesis: VI. Reactions with vinyl ethers
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Reactions of acetyl iodide with butyl vinyl ether, 1,2-divinyloxyethane, phenyl vinyl ether, 1,4-di-vinyloxybenzene, and divinyl ether were studied. Vinyl ethers derived from aliphatic alcohols (butyl vinyl ether and 1,2-divinyloxyethane) react with acetyl iodide in a way similar to ethyl vinyl ether, i.e., with cleavage of both O-Csp2 and Alk-O ether bonds. From butyl vinyl ether, a mixture of vinyl iodide, butyl acetate, vinyl acetate, and butyl iodide is formed, while 1,2-divinyloxyethane gives rise to vinyl iodide, vinyl acetate, and 2-iodoethyl acetate. The reaction of acetyl iodide with divinyl ether involves cleavage of only one O-Csp2 bond, yielding vinyl acetate and vinyl iodide. In the reactions of acetyl iodide with phenyl vinyl ether and 1,4-divinyloxybenzene, only the O-CVin bond is cleaved, whereas the O-CAr bond remains intact.
- Voronkov,Trukhina,Vlasova
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p. 467 - 469
(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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- A facile conversion of thiols to alkyl halides by triphenylphosphine/N-halosuccinimides
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Thiols are efficiently converted to alkyl halides in high to excellent yields when treated with triphenylphosphin/N-halosuccinimide (halogen: Br,Cl, and I) in dichloromethane at room temperature.
- Iranpoor,Firouzabadi,Aghapour
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p. 1176 - 1178
(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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- Thiocyanation of alkyl halides with alkyl thiocyanates in the presence of quaternary phosphonium halides
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Alkyl thiocyanates undergo simple SN2 reactions with the counter ions of quaternary phosphonium salts in nonpolar solvents and thiocyanate ions are liberated as the leaving ion. Depending on the nucleophile, the reaction proceeded irreversibly or reversibly. The reaction of benzyl thiocyanate with azide ions afforded a quantitative yield of benzyl azide. The reactions of alkyl thiocyanates with halide ions gave an equilibrium mixture where the reverse reaction of the alkyl halides produced with the liberated thiocyanate ions took place simultaneously. Thus, thiocyanate-halide exchange reactions between an alkyl thiocyanate and an alkyl halide were possible in the presence of a catalytic amount of a quaternary salt.
- Ohtani, Noritaka,Murakawa, Shigeki,Watanabe, Kohji,Tsuchimoto, Daisuke,Sato, Daiki
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p. 1851 - 1856
(2007/10/03)
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- One-step cross-coupling reaction of functionalized alkyl iodides with aryl halides by the use of an electrochemical method
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Organozinc compounds of functionalized alkyl iodide carrying an alkoxycarbonyl, cyano or alkenyl group were prepared in high yields under mild conditions (0°C-r.t., 10min in DMF) by the reaction of iodides with an electrogenerated reactive zinc (EGZn). Cross-coupling of the organozinc compounds with various aryl halides in the presence of 5 mol% Pd(P(o- Tol)3)2Cl2 in THF gave the corresponding cross-coupled products in moderate to high yields. These cross-coupling reactions can be also achieved in one step and in one pot by the use of an electrochemical method utilizing a Pt cathode and Zn anode.
- Kurono, Nobuhito,Sugita, Kazuya,Takasugi, Shingo,Tokuda, Masao
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p. 6097 - 6108
(2007/10/03)
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- Synthesis of new quaternary phosphonium salts
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A number of hitherto unknown phosphonium salts were synthesized by reaction of diisopropyliodophosphine with organic halides. A new procedure was proposed for preparation of alkyl iodides.
- Kabachnik,Khomutova,Beletskaya
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- Primary and secondary 5-(alkyloxy)thianthrenium perchlorates. Characterization with 1H NMR spectroscopy, reactions with iodide and bromide ion, and thermal decomposition in solution
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A series of 5-(alkyloxy)thianthrenium perchlorates has been made in which the alkyl group is primary (1a-1p) and secondary (2a-2g). Preparations were carded out by reaction of the corresponding alkanol with thianthrene cation radical perchlorate in CH2Cl2 solution followed by precipitation of the perchlorate salt with dry ether. 1H NMR spectroscopy reveals that the presence of a stereogenic center in the alkyl group causes inequivalence in the ordinarily paired protons (e.g., H-4, H-6) of the thianthrenium ring. Reaction of iodide and bromide ion with primary alkyl-group compounds (e.g., methyl, ethyl, propyl, butyl) gave the alkyl halide in very good yield and by a second-order kinetic displacement. The second product was thianthrene 5- oxide (ThO). Rate constants for some of these reactions are reported. Reaction of secondary alkyl group compounds (e.g., 2-propyl, 2-pentyl, 2- hexyl, and 3-hexyl) with iodide ion gave good yields of alkyl iodide but also increasing evidence for a side reaction at the sulfonium sulfur, leading to I2, thianthrene, and secondary alkanol. Decomposition of some compounds at 100°C in solution (acetonitrile or 1,2-dichloroethane) was studied and gave alkene(s) and ThO.
- Zhao, Wenyi,Shine, Henry J.
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p. 695 - 702
(2007/10/03)
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- Novel reactions of perfluoroalkylphenyl sulfides with organolithium reagents
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The reaction of anisole with organolithium reagents, commonly known as ortho-directed metallation, is of considerable synthetic utility in organic chemistry and as such has attracted considerable attention in recent years.Over the past 50 years, several mechanisms have been proposed to account for the observed regioselective metallation.For the first time, the reaction of perfluoroalkylphenyl sulfides with organolithium reagents has been investigated and found to furnish products resulting from the replacement of the perfluoroalkyl moieties with alkyl groups derived from the metallating agents.Phenyltrifluoromethyl ether, the anisole analog, failed to undergo metallation.A rationalization for the formation of unusual products via mediation of a single-electron-transfer process is presented in this paper together with the spectral data of the products. - Keywords: Reactions; Perfluoroalkylphenyl sulfides; Organolithium reagents; NMR spectroscopy; Mass spectrometry; Orthometallation
- Munavalli, S.,Hassner, A.,Rossman, D. I.,Singh, S.,Rohrbaugh, D. K.,Ferguson, C. P.
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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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- SULFOXIMINE AND SULDODIIMINE MATRIX METALLOPROTEINASE INHIBITORS
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Novel sulfoximine and sulfodiimine matrix metalloproteinase inhibitors of the formula, STR1 wherein: R 1 is selected from the group consisting of lower-alkyl, hydroxy lower-alkyl, amino lower-alkyl, carbamoyl lower-alkyl, lower-alkyl carbonyl, lower-alkyoxyalkyl, aralkyl and heteroaralkyl;X is NH or O;R 2 is selected from the group consisting of hydrogen, lower-alkyl and aralkyl;R 3 is selected from the group consisting of hydrogen, lower-alkyl, amino lower-alkyl, guanyl lower-alkyl, aralkyl and heteroaralkyl; andR 4 is selected from the group consisting of lower alkyl, aralkyl and--CH(R 5)--C(O)NH 2, wherein R 5 is selected from the group consisting of hydrogen, lower-alkyl, amino lower-alkyl, guanyl lower-alkyl, imidazoylalkyl, hydroxymethyl, 1-hydroxyethyl, mercapto lower-alkyl, and methylthio lower-alkyl;useful for modulating physiological functions or treating diseases and disease conditions associated with matrix metalloproteinase modulation.
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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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- Hypervalent iodine in carbon-carbon bond forming reactions. A new reaction of hypervalent iodine compounds and organolithium reagents
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Hypervalent iodine compounds react with organolithium reagents instantaneously even at -80°C resulting in the formation of hydrocarbons. Our findings indicate that the carbon-carbon bond formation is the result of ligand exchange and second displacement on the carbon bonded to iodine.
- Barton,Jaszberenyi Cs.,Lessmann,Timar
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p. 8881 - 8890
(2007/10/02)
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- Preparation of 6-0-alkylelsamicin A derivatives
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This invention relates to novel elsamicin A derivatives having 6-O-alkyl substitutent, a process for producing said elsamicin A derivatives, antitumor compositions containing the same as the active ingredient, and a method for therapy using said compositions.
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- Diiodosilane. 2. A Multipurpose Reagent for Hydrolysis and Reductive Iodination of Ketals, Acetals, Ketones, and Aldehydes
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The reaction patterns of diiodosilane (SiH2I2, DIS) with ketals, acetals, ketones, and aldehydes were explored.The reagent may be used for mild cleavage of ketals and acetals either hydrolytically to give the parent carbonyl functionality or reductively to produce the corresponding alkyl iodide.At low temperatures (-42 deg C) and short reaction times (few minutes), catalytic amounts (5-10 molpercent) of DIS provide clean deprotection of various ketals and acetals to yield ketones and aldehydes, with no apparent reduction of the latter.At temperatures above 0 deg C, DIS effectively reduces ketals and acetals to iodoalkanes.This reduction is quite general both with respect to ketals and acetals and unprotected ketones and aldehydes.Reaction rates, however, are strikingly dependent on the substrate, with the following tendencies: (a) aromatic functionalities are generally reduced much faster than their aliphatic analogues; (b) ketals and acetals are rapidly reduced to the corresponding iodoalkanes, while free aldehydes, and particularly ketones, are essentially inert under the reaction conditions (but can be significantly activated by catalytic amounts of iodine); (c) dimethyl ketals form the parent ketones preferentially, while all other ketals, including diethyl ketals and dioxolanes, are reduced to iodoalkanes.
- Keinan, E.,Perez, D.,Sahai, M.,Shvily, R.
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p. 2927 - 2938
(2007/10/02)
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- SYNTHESIS OF ALKYL HALIDES UNDER NEUTRAL CONDITIONS
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Primary and secondary alcohols are efficiently converted to the corresponding alkyl halides under neutral conditions.
- Munyemana, Francois,Frisque-Hesbain, Anne-Marie,Devos, Alain,Ghosez, Leon
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p. 3077 - 3080
(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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- Process for preparation of carboxylic acid ester containing fluorine
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Process for the preparation of carboxylic acid ester containing fluorine comprises the reaction of the reaction mixture obtained by the reaction of an organic halogen compound containing fluorine expressed by a general formula, , X - Rf- X′, , (in which, X and X′ independently stand for halogen atoms and Rfis an optionally fluorinated hydrocarbon) with carbon dioxide in the presence of zinc, with a halogenated hydrocarbon expressed by a general formula,, RY, , (in which R is an optionally fluorinated hydrocarbon and Y is a chlorine, bromine or iodine atom).
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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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- Functionalized Ethylene Oligomers as Phase-Transfer Catalysts
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Ethylene oligomers with Mv in the range 1000-3000 containing terminal groups such as crown ethers, azacrown ethers, and phosphonium salts have been prepared and used as phase-transfer catalysts.These oligomeric catalysts have solubility properties similar to polyethylene in that they are insoluble at 25 deg C but dissolve in organic solutions at elevated (90-110 deg C) temperatures.Such oligomeric phase-transfer catalysts have activities comparable to their low molecular wait congeners and to activities reported for insoluble polystyrene-bound phase-transfer catalysts.After these oligomeric catalysts have been used in a reaction at 100 deg C, thay can be readily separated from the reaction products by cooling to form a precipitate, which can be isolated by filtration.Such catalysts may be reused without loss of activity.These catalysts are also effective in "solid-liquid" phase-transfer reactions in which an inorganic solid is suspended in a hot organic solution containing catalyst and substrate.
- Bergbreiter, David E.,Blanton, J. R.
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p. 5828 - 5833
(2007/10/02)
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- NEW PREPARATION OF ALKYL IODIDES FROM THE CORRESPONDING ALCOHOLS
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It is shown that alkyl iodides can be obtained from the corresponding alkyl α-chloroethyl carbonate and NaI or by direct reaction between the alcohol, α-chloroethyl chloroformate and NaI.
- Brunet, J. J.,Laurent, H.,Caubere, P.
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p. 5445 - 5446
(2007/10/02)
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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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- The efficiency of diphenylalkylsulfonium salts as alkylating agents
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A series of the title reagents have been used for the alkylation of a number of nucleophiles including iodide, cyanide, thiocyanate and fluoride ions as well as ethyl acetoacetate, phenylacetonitrile and a variety of nitrogen heterocyclic compounds.The results compared favorably with literature methods.
- Badet, Bernard,Julia, Marc,Lefebvre, Christian
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p. 431 - 434
(2007/10/02)
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- Novel process
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A novel catalyst, possessing phase transfer properties contains an alumina or silica substrate bearing poly(oxyethylene) or poly(oxypropylene) moieties bonded through a silicon atom to the substrate.
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