- Merging Halogen-Atom Transfer (XAT) and Cobalt Catalysis to Override E2-Selectivity in the Elimination of Alkyl Halides: A Mild Route towardcontra-Thermodynamic Olefins
-
We report here a mechanistically distinct tactic to carry E2-type eliminations on alkyl halides. This strategy exploits the interplay of α-aminoalkyl radical-mediated halogen-atom transfer (XAT) with desaturative cobalt catalysis. The methodology is high-yielding, tolerates many functionalities, and was used to access industrially relevant materials. In contrast to thermal E2 eliminations where unsymmetrical substrates give regioisomeric mixtures, this approach enables, by fine-tuning of the electronic and steric properties of the cobalt catalyst, to obtain high olefin positional selectivity. This unprecedented mechanistic feature has allowed access tocontra-thermodynamic olefins, elusive by E2 eliminations.
- Zhao, Huaibo,McMillan, Alastair J.,Constantin, Timothée,Mykura, Rory C.,Juliá, Fabio,Leonori, Daniele
-
supporting information
p. 14806 - 14813
(2021/09/18)
-
- Oxidative Cleavage of Alkenes by O2with a Non-Heme Manganese Catalyst
-
The oxidative cleavage of C═C double bonds with molecular oxygen to produce carbonyl compounds is an important transformation in chemical and pharmaceutical synthesis. In nature, enzymes containing the first-row transition metals, particularly heme and non-heme iron-dependent enzymes, readily activate O2 and oxidatively cleave C═C bonds with exquisite precision under ambient conditions. The reaction remains challenging for synthetic chemists, however. There are only a small number of known synthetic metal catalysts that allow for the oxidative cleavage of alkenes at an atmospheric pressure of O2, with very few known to catalyze the cleavage of nonactivated alkenes. In this work, we describe a light-driven, Mn-catalyzed protocol for the selective oxidation of alkenes to carbonyls under 1 atm of O2. For the first time, aromatic as well as various nonactivated aliphatic alkenes could be oxidized to afford ketones and aldehydes under clean, mild conditions with a first row, biorelevant metal catalyst. Moreover, the protocol shows a very good functional group tolerance. Mechanistic investigation suggests that Mn-oxo species, including an asymmetric, mixed-valent bis(μ-oxo)-Mn(III,IV) complex, are involved in the oxidation, and the solvent methanol participates in O2 activation that leads to the formation of the oxo species.
- Bennett, Elliot L.,Brookfield, Adam,Guan, Renpeng,Huang, Zhiliang,Mcinnes, Eric J. L.,Robertson, Craig M.,Shanmugam, Muralidharan,Xiao, Jianliang
-
supporting information
p. 10005 - 10013
(2021/07/19)
-
- Structural elucidation of a methylenation reagent of esters: Synthesis and reactivity of a dinuclear titanium(iii) methylene complex
-
Transmetallation of a zinc methylene complex [ZnI(tmeda)]2(μ-CH2) with a titanium(iii) chloride [TiCl3(tmeda)(thf)] produced a titanium methylene complex. The X-ray diffraction study displayed a dinuclear methylene structure [TiCl(tmeda)]2(μ-CH2)(μ-Cl)2. Treatment of an ester with the titanium methylene complex resulted in methylenation of the ester carbonyl to form a vinyl ether. The titanium methylene complex also reacted with a terminal olefin, resulting in olefin-metathesis and olefin-homologation. Cyclopropanation by methylene transfer from the titanium methylene proceeded by use of a 1,3-diene. The mechanistic study of the cyclopropanation reaction by the density functional theory calculations was also reported.
- Kurogi, Takashi,Kuroki, Kaito,Moritani, Shunsuke,Takai, Kazuhiko
-
p. 3509 - 3515
(2021/03/29)
-
- Nickel-Catalyzed Asymmetric Reductive Arylbenzylation of Unactivated Alkenes
-
Herein, we report a nickel-catalyzed asymmetric two-component reductive dicarbofunctionalization of aryl iodide-tethered unactivated alkenes using benzyl chlorides as the challenging coupling partner. This arylbenzylation reaction enables the efficient synthesis of diverse benzene-fused cyclic compounds bearing a quaternary stereocenter with a high tolerance of sensitive functionalities in highly enantioselective manner. The preliminary mechanistic investigations suggest a radical chain reaction mechanism.
- Jin, Youxiang,Yang, Haobo,Wang, Chuan
-
supporting information
p. 2724 - 2729
(2020/04/02)
-
- Nickel-Catalyzed Asymmetric Reductive 1,2-Carboamination of Unactivated Alkenes
-
Starting from diverse alkene-tethered aryl iodides and O-benzoyl-hydroxylamines, the enantioselective reductive cross-electrophilic 1,2-carboamination of unactivated alkenes was achieved using a chiral pyrox/nickel complex as the catalyst. This mild, modular, and practical protocol provides rapid access to a variety of β-chiral amines with an enantioenriched aryl-substituted quaternary carbon center in good yields and with excellent enantioselectivities. This process reveals a complementary regioselectivity when compared to Pd and Cu catalysis.
- He, Jun,Xue, Yuhang,Han, Bo,Zhang, Chunzhu,Wang, You,Zhu, Shaolin
-
supporting information
p. 2328 - 2332
(2020/01/08)
-
- Nickel-Catalyzed Reductive Arylalkylation via a Migratory Insertion/Decarboxylative Cross-Coupling Cascade
-
Reported is a nickel-catalyzed reductive arylalkylation of unactivated alkenes tethered to aryl iodides with redox active N-hydroxyphthalimide esters as the alkyl source through successful merging of migratory insertion and decarboxylative cross-coupling in a cascade. This new method avoids the use of pregenerated organometallic reagents and thus enables the synthesis of diverse benzene-fused carbo- and heterocyclic compounds with high tolerance of a wide range of functional groups.
- Jin, Youxiang,Yang, Haobo,Wang, Chuan
-
supporting information
p. 7602 - 7608
(2019/10/02)
-
- Ni-catalysed reductive arylalkylation of unactivated alkenes
-
In this protocol Ni-catalysed reductive arylalkylation of unactivated alkenes tethered to aryl bromides with primary alkyl bromides has been accomplished, providing a new path to construct diverse benzene-fused carbo- and heterocyclic cores including inda
- Jin, Youxiang,Wang, Chuan
-
p. 1780 - 1785
(2019/02/15)
-
- Aminoxyl-Catalyzed Electrochemical Diazidation of Alkenes Mediated by a Metastable Charge-Transfer Complex
-
We report the development of a new aminoxyl radical catalyst, CHAMPO, for the electrochemical diazidation of alkenes. Mediated by an anodically generated charge-transfer complex in the form of CHAMPO-N3, radical diazidation was achieved across a broad scope of alkenes without the need for a transition metal catalyst or a chemical oxidant. Mechanistic data support a dual catalytic role for the aminoxyl serving as both a single-electron oxidant and a radical group transfer agent.
- Siu, Juno C.,Parry, Joseph B.,Lin, Song
-
supporting information
p. 2825 - 2831
(2019/02/14)
-
- Direct Hydrofluorination of Methallyl Alkenes Using a Methanesulfonic Acid/Triethylamine Trihydrofluoride Combination
-
The use of a methanesulfonic acid/triethylamine trihydrofluoride combination for the direct hydrofluorination of methallyl-containing substrates is reported. Under those metal-free conditions that use readily available, cheap, and easy to handle reagents,
- Bertrand, Xavier,Paquin, Jean-Fran?ois
-
supporting information
p. 9759 - 9762
(2019/11/28)
-
- Controllable Isomerization of Alkenes by Dual Visible-Light-Cobalt Catalysis
-
We report herein that thermodynamic and kinetic isomerization of alkenes can be accomplished by the combination of visible light with Co catalysis. Utilizing Xantphos as the ligand, the most stable isomers are obtained, while isomerizing terminal alkenes over one position can be selectively controlled by using DPEphos as the ligand. The presence of the donor–acceptor dye 4CzIPN accelerates the reaction further. Transformation of exocyclic alkenes into the corresponding endocyclic products could be efficiently realized by using 4CzIPN and Co(acac)2 in the absence of any additional ligands. Spectroscopic and spectroelectrochemical investigations indicate CoI being involved in the generation of a Co hydride, which subsequently adds to alkenes initiating the isomerization.
- Meng, Qing-Yuan,Schirmer, Tobias E.,Katou, Kousuke,K?nig, Burkhard
-
supporting information
p. 5723 - 5728
(2019/04/03)
-
- Nickel-catalyzed asymmetric intramolecular reductive heck reaction of unactivated alkenes
-
An asymmetric Ni-catalyzed intramolecular reductive Heck reaction of unactivated alkenes tethered to aryl bromides has been accomplished, providing a variety of benzene-fused cyclic compounds bearing a quaternary stereogenic center in good to excellent yi
- Yang, Feiyan,Jin, Youxiang,Wang, Chuan
-
p. 6989 - 6994
(2019/09/30)
-
- Radical Deoxychlorination of Cesium Oxalates for the Synthesis of Alkyl Chlorides
-
A radical deoxychlorination of cesium oxalates has been developed for the preparation of hindered secondary and tertiary alkyl chlorides. The reaction tolerates a number of functional groups, including ketones, alcohols, and amides, and provides complementary reactivity to standard deoxychlorination reactions proceeding by heterolytic mechanisms. Preliminary studies demonstrate that the developed conditions can also be applied to deoxybromination and deoxyfluorination reactions.
- Su, Justin Y.,Grünenfelder, Denise C.,Takeuchi, Kohei,Reisman, Sarah E.
-
supporting information
p. 4912 - 4916
(2018/08/24)
-
- An investigation into the role of 2,6-lutidine as an additive for the RuCl3-NaIO4 mediated oxidative cleavage of olefins to ketones
-
2,6-Lutidine has been identified as a beneficial additive for the oxidative cleavage of olefins to ketones by NaIO4 in the presence of catalytic RuCl3, improving the yield and shortening the reaction times. In the absence of 2,6-lutidine reactions stalled at the diol intermediate with incomplete conversion to the desired ketones. The reaction protocol described herein also avoids the use of harmful solvents such as CCl4 and DCE and is tolerant of a range of functional groups.
- Watson, David W.,Gill, Matthew,Kemmitt, Paul,Lamont, Scott G.,Popescu, Mihai V.,Simpson, Iain
-
supporting information
p. 4479 - 4482
(2018/11/23)
-
- Mild Ring-Opening 1,3-Hydroborations of Non-Activated Cyclopropanes
-
The Brown hydroboration reaction, first reported in 1957, is the addition of B?H across an olefin in an anti-Markovnikov fashion. Here, we solved a long-standing problem on mild 1,3-hydroborations of non-activated cyclopropanes. A three-component system including cyclopropanes, boron halides, and hydrosilanes has been developed for borylative ring-opening of cyclopropanes following the anti-Markovnikov rule, under mild reaction conditions. Density functional theory (M06-2X) calculations show that the preferred pathway involves a cationic boron intermediate which is quenched by hydride transfer from the silane.
- Wang, Di,Xue, Xiao-Song,Houk, Kendall N.,Shi, Zhuangzhi
-
supporting information
p. 16861 - 16865
(2018/11/27)
-
- Nickel-Catalyzed Direct Synthesis of Aryl Olefins from Ketones and Organoboron Reagents under Neutral Conditions
-
Nickel-catalyzed addition of arylboron reagents to ketones results in aryl olefins directly. The neutral condition allows acidic protons of alcohols, phenols, and malonates to be present, and fragile structures are also tolerated.
- Lei, Chuanhu,Yip, Yong Jie,Zhou, Jianrong Steve
-
supporting information
p. 6086 - 6089
(2017/05/08)
-
- Water-Enabled Catalytic Asymmetric Michael Reactions of Unreactive Nitroalkenes: One-Pot Synthesis of Chiral GABA-Analogs with All-Carbon Quaternary Stereogenic Centers
-
Water enables new catalytic reactions for otherwise unreactive substrate systems. Under the “on water” reaction conditions, extremely unreactive β,β-disubstituted nitroalkenes smoothly underwent enantioselective Michael addition reactions with dithiomalonates using a chiral squaramide catalyst, affording both enantiomers of highly enantioenriched Michael adducts with all-carbon-substituted quaternary centers. The developed “on water” protocol was successfully applied for the scalable one-pot syntheses of chiral GABA analogs with all-carbon quaternary stereogenic centers at the β-position, which might show highly interesting pharmaceutical properties.
- Sim, Jae Hun,Song, Choong Eui
-
supporting information
p. 1835 - 1839
(2017/02/05)
-
- Asymmetric Nitrone Synthesis via Ligand-Enabled Copper-Catalyzed Cope-Type Hydroamination of Cyclopropene with Oxime
-
We report realization of the first enantioselective Cope-type hydroamination of oximes for asymmetric nitrone synthesis. The ligand promoted asymmetric cyclopropene "hydronitronylation" process employs a Cu-based catalytic system and readily available starting materials, operates under mild conditions and displays broad scope and exceptionally high enantio- and diastereocontrol. Preliminary mechanistic studies corroborate a CuI-catalytic profile featuring an olefin metalla-retro-Cope aminocupration process as the key C-N bond forming event. This conceptually novel reactivity enables the first example of highly enantioselective catalytic nitrone formation process and will likely spur further developments that may significantly expedite chiral nitrone synthesis.
- Li, Zhanyu,Zhao, Jinbo,Sun, Baozhen,Zhou, Tingting,Liu, Mingzhu,Liu, Shuang,Zhang, Mengru,Zhang, Qian
-
supporting information
p. 11702 - 11705
(2017/09/07)
-
- Rapid access to cyclopentadiene derivatives through gold-catalyzed cycloisomerization of ynamides with cyclopropenes by preferential activation of alkenes over alkynes
-
In this communication, gold-catalyzed intermolecular cycloisomerization of cyclopropenes and ynamides is investigated. The current transformation displayed an activation priority of double bonds over triple bonds by the cationic gold catalyst, giving the corresponding cyclopentadienes in good to excellent yields. Additionally, this protocol can be expanded to a one-pot two-step procedure for the synthesis of substituted cyclopentanones.
- Cheng, Xing,Zhu, Lei,Lin, Meijun,Chen, Jianxin,Huang, Xueliang
-
supporting information
p. 3745 - 3748
(2017/04/03)
-
- Palladium-Catalyzed Electrochemical Allylic Alkylation between Alkyl and Allylic Halides in Aqueous Solution
-
A new route for the direct cross-coupling of alkyl and allylic halides using electrochemical technique has been developed in aqueous media under air. Catalyzed by Pd(OAc)2, the Zn-mediated allylic alkylations proceed smoothly between a full range of alkyl halides (primary, secondary, and tertiary) and substituted allylic halides. Protection-deprotection of acidic hydrogen in the substrates is avoided.
- Lai, Yin-Long,Huang, Jing-Mei
-
supporting information
p. 2022 - 2025
(2017/04/28)
-
- Hantzsch Ester as a Photosensitizer for the Visible-Light-Induced Debromination of Vicinal Dibromo Compounds
-
The debromination of vicinal dibromo compounds to generate alkenes usually requires harsh reaction conditions and the addition of catalysts. Just recently the visible-light-induced debromination of vicinal dibromo compounds emerged as a possible alternative to commonly used methods, but the substrate scope of this reaction is limited and a photocatalyst is necessary for the successful conversion of the starting compounds. A catalyst-free visible-light-induced debromination of vicinal dibromo compounds with a base-activated Hantzsch ester as photosensitizer is reported. The method has a wide substrate scope and a broad functional-group compatibility.
- Chen, Wenxin,Tao, Huachen,Huang, Wenhao,Wang, Guoqiang,Li, Shuhua,Cheng, Xu,Li, Guigen
-
supporting information
p. 9546 - 9550
(2016/07/14)
-
- Synthesis of α-Tertiary Amine Derivatives by Intermolecular Hydroamination of Unfunctionalized Alkenes with Sulfamates under Trifluoromethanesulfonic Acid Catalysis
-
An efficient and mild trifluoromethanesulfonic acid-catalyzed hydroamination of unfunctionalized alkenes to afford α-tertiary amine derivatives at temperatures as low as room temperature is reported. 2,2,2-Trifluoroethyl sulfamate was found to be the optimal nitrogen source because its good solubility in both organic solvents and water facilitated both conversion and purification. The reaction conditions were compatible with a variety of substrate functional groups and afforded moderate to good yields. The desired amine compounds could be obtained easily by means of a mild, one-pot, redox-neutral deprotection procedure. Caryolane amine was synthesized with excellent chemo- and regioselectivities by means of a cascade hydroamination reaction of β-caryophyllene.
- Fei, Jun,Wang, Zhen,Cai, Zheren,Sun, Hao,Cheng, Xu
-
supporting information
p. 4063 - 4068
(2016/01/25)
-
- Rh(II)-Catalyzed [2,3]-Sigmatropic Rearrangement of Sulfur Ylides Derived from Cyclopropenes and Sulfides
-
(Chemical Equation Presented) A new type of Rh2(OAc)4-catalyzed [2,3]-sigmatropic rearrangement of sulfur ylides is reported. A series of cyclopropenes were successfully employed for [2,3]-sigmatropic rearrangement by a reaction with either allylic or propargylic sulfides. Under the optimized conditions, the reaction afforded the products in moderate to excellent yields. In these transformations, the vinyl metal carbenes generated in situ from the cyclopropenes were effectively trapped by sulfides, resulting in the formation of corresponding products upon [2,3]-sigmatropic rearrangements.
- Zhang, Hang,Wang, Bo,Yi, Heng,Zhang, Yan,Wang, Jianbo
-
supporting information
p. 3322 - 3325
(2015/07/15)
-
- Amines vs. N-Oxides as Organocatalysts for Acylation, Sulfonylation and Silylation of Alcohols: 1-Methylimidazole N-Oxide as an Efficient Catalyst for Silylation of Tertiary Alcohols
-
A comparison of the relative catalytic efficiencies of Lewis-basic amines vs. N-oxides for the acylation, sulfonylation and silylation of primary, secondary and tertiary alcohols is reported. Whilst the amines are generally superior to the N-oxides for acylation, the N-oxides are superior for sulfonylation and silylation. In particular, 1-methylimidazole N-oxide (NMI-O) is found to be a highly efficient catalyst for sulfonylation and silylation reactions. To the best of our knowledge, NMI-O is the first amine or N-oxide Lewis basic organocatalyst capable of promoting the efficient silylation of tert-alcohols in high yield with low catalyst loading under mild reaction conditions.
- Murray, James I.,Spivey, Alan C.
-
p. 3825 - 3830
(2016/01/25)
-
- Iron-catalyzed cross-coupling of unactivated secondary alkyl thio ethers and sulfones with aryl grignard reagents
-
The first systematic investigation of unactivated aliphatic sulfur compounds as electrophiles in transition-metal-catalyzed cross-coupling are described. Initial studies focused on discerning the structural and electronic features of the organosulfur substrate that enable the challenging oxidative addition to the C(sp3)-S bond. Through extensive optimization efforts, an Fe(acac)3-catalyzed cross-coupling of unactivated alkyl aryl thio ethers with aryl Grignard reagents was realized in which a nitrogen "directing group" on the S-aryl moiety of the thio ether served a critical role in facilitating the oxidative addition step. In addition, alkyl phenyl sulfones were found to be effective electrophiles in the Fe(acac) 3-catalyzed cross-coupling with aryl Grignard reagents. For the latter class of electrophile, a thorough assessment of the various reaction parameters revealed a dramatic enhancement in reaction efficiency with an excess of TMEDA (8.0 equiv). The optimized reaction protocol was used to evaluate the scope of the method with respect to both the organomagnesium nucleophile and sulfone electrophile.
- Denmark, Scott E.,Cresswell, Alexander J.
-
supporting information
p. 12593 - 12628
(2014/01/17)
-
- METHOD FOR PRODUCING COMPOUND WITH CARBONYL GROUP BY USING RUTHENIUM CARBONYL COMPLEX HAVING TRIDENTATE LIGAND AS DEHYDROGENATION OXIDATION CATALYST
-
Provided by the present invention is a method for efficient oxidation of alcohols by using, as a catalyst for dehydrogenation oxidation, a ruthenium complex which can be easily produced and easily handled and is obtainable at a relatively low cost. The invention relates to a method of producing a compound having a carbonyl group by dehydrogenation oxidation of alcohols by using as a catalyst the ruthenium carbonyl complex represented by the following general formula (1) RuXY(CO)(L) (1) (in the general formula (1), X and Y may be the same or different from each other and represent an anionic ligand, and L represents a tridentate aminodiphosphine ligand).
- -
-
Page/Page column 46-48
(2012/11/07)
-
- Tetramethylfluoroformamidinium hexafluorophosphate (TFFH) as a mild deoxofluorination reagent
-
The solid, air-stable peptide coupling reagent TFFH (tetramethylfluoroformamidinium hexafluorophosphate) was found to activate a variety of alcohols towards deoxofluorination. These conditions are compatible with carbonyl functional groups thus offering interesting possibilities for the application to sensitive molecules. Georg Thieme Verlag Stuttgart · New York.
- Bellavance, Gabriel,Dubé, Pascal,Nguyen, Bao
-
experimental part
p. 569 - 572
(2012/04/17)
-
- Straightforward conversion of alcohols into nitriles
-
The reaction of various alcohols with cyanogen bromide, triphenylphosphine, and a base afforded the corresponding nitrile in satisfactory yields. Copyright
- Tarrade-Matha, Aurelie,Pillon, Florence,Doris, Eric
-
experimental part
p. 1646 - 1649
(2010/07/09)
-
- Palladium-catalyzed desulfinylative C-C allylation of Grignard reagents and enolates using allylsulfonyl chlorides and esters
-
2-Methylprop-2-ene-, prop-2-ene-, 1-methylprop-2-ene-, and (E)-but-2-enesulfonyl chlorides have been used as electrophilic partners in desulfinylative palladium-catalyzed C-C coupling with Grignard reagents and sodium salts of dimethyl malonate and methyl
- Rao Volla, Chandra M.,Dubbaka, Srinivas Reddy,Vogel, Pierre
-
experimental part
p. 504 - 511
(2009/04/07)
-
- Rhodium(I)-catalyzed intramolecular hydroacylation of 4,6-dienals: Novel synthesis of cycloheptenones
-
Rhodium(I)-catalyzed hydroacylation of 4,6-dienals was investigated. Hydroacylation of 4,6-dienals with a substituent at the C7 position produced cycloheptenone derivatives as the major products, while the cyclization of 4,6-dienals with no substituent at the terminus of the diene moiety preferentially gave cyclopentanone derivatives. The olefinic geometry of the diene moiety in 4,6-dienals also affected the reaction course, and the cyclization of substrates with an E-olefin at the C6 position produced cycloheptenone derivatives as the major products, while a cyclopentanone derivative was obtained from a substrate with a Z-olefin at the C6 position. Georg Thieme Verlag Stuttgart.
- Oonishi, Yoshihiro,Mori, Miwako,Sato, Yoshihiro
-
p. 2323 - 2336
(2008/02/13)
-
- Iron-catalyzed cross-coupling of alkyl halides with alkenyl Grignard reagents
-
(Chemical Equation Presented) Cheap and safe: An iron-catalyzed cross-coupling reaction between alkyl halides and alkenyl Grignard reagents is described. This C-C bond coupling reaction is promoted by the cheap and nontoxic FeCl3 and displays good tolerance against various functional groups.
- Guerinot, Amandine,Reymond, Sebastien,Cossy, Janine
-
p. 6521 - 6524
(2008/09/16)
-
- Cyanation of alcohols with diethyl cyanophosphonate and 2,6-dimethyl-1,4-benzoquinone by a new type of oxidation-reduction condensation
-
Cyanation of various alcohols by a new type of oxidation-reduction condensation is described. Primary alkyl diphenylphosphinites, 2,6-dimethyl-1,4-benzoquinone (DMBQ), and diethyl cyanophosphonate gave the corresponding nitriles in high yields. During the above experiment on cyanation of 4-phenylbutan-2-ol, the unexpected formation of a mixture of nitrile and isocyanide was observed. After careful examination of the reaction conditions, selective synthesis of isocyanides from secondary alcohols was successfully accomplished by the use of zinc oxide (ZnO) as an additive. Reaction of tertiary alcohols provided the corresponding isocyanides exclusively in the absence of an additive. Cyanation of optically active alcohols was tried in order to clarify the stereochemistry of this reaction, and the reaction was thus proved to proceed with the inversion of configuration.
- Masutani, Kouta,Minowa, Tomofumi,Hagiwara, Yoshiaki,Mukaiyama, Teruaki
-
p. 1106 - 1117
(2007/10/03)
-
- Hydrazines and azides via the metal-catalyzed hydrohydrazination and hydroazidation of olefins
-
The discovery, study, and implementation of the Co- and Mn-catalyzed hydrohydrazination and hydroazidation reactions of olefins are reported. These reactions are equivalent to direct hydroaminations of C-C double bonds with protected hydrazines or hydrazoic acid but are based on a different concept in which the H and the N atoms come from two different reagents, a silane and an oxidizing nitrogen source (azodicarboxylate or sulfonyl azide). The hydrohydrazination reaction using di-tert-butyl azodicarboxylate is characterized by its ease of use, large functional group tolerance, and broad scope, including mono-, di-, tri-, and tetrasubstituted olefins. Key to the development of the hydroazidation reaction was the use of sulfonyl azides as nitrogen sources and the activating effect of tert-butyl hydroperoxide. The reaction was found to be efficient for the functionalization of mono-, di-, and trisubstituted olefins, and only a few functional groups are not tolerated. The alkyl azides obtained are versatile intermediates and can be transformed to the free amines or triazoles without isolation of the azides. Preliminary mechanistic investigations suggest a rate-limiting hydrocobaltation of the alkene, followed by an amination reaction. Radical intermediates cannot be ruled out and may be involved.
- Waser, Jerome,Gaspar, Boris,Nambu, Hisanori,Carreira, Erick M.
-
p. 11693 - 11712
(2007/10/03)
-
- Straightforward conversion of alcohols into dibenzenesulfonimides
-
The reaction of various alcohols with N-fluorodibenzenesulfonimide and triphenylphosphine leads to the corresponding dibenzenesulfonylated amines in high yields.
- Giovanelli, Emerson,Doris, Eric,Rousseau, Bernard
-
p. 8457 - 8458
(2007/10/03)
-
- Cobalt-catalyzed hydroazidation of olefins: Convenient access to alkyl azides
-
Conversion of olefins to azides was achieved with high Markovnikov selectivity for a broad range of alkenes using 6 mol % Co(BF4)·6H2O and ligand 1, with 3 equiv of TsN3 as nitrogen source and simple silanes (PhSiH3, TMDSO). Copyright
- Waser, Jerome,Nambu, Hisanori,Carreira, Erick M.
-
p. 8294 - 8295
(2007/10/03)
-
- Specific features of thermal degradation of polypropylene in the presence of magnesium hydroxide
-
Specific features of thermal oxidative degradation of polypropylene and its composite with Mg(OH)2 were studied by pyrolytic gas chromatography-mass spectrometry and thermal gravimetric analysis.
- Koverzanova,Usachev,Shilkina,Lomakin,Gumargalieva,Zaikov
-
p. 445 - 448
(2007/10/03)
-
- Highly efficient synthesis of terminal alkenes from ketones
-
(Chemical Equation Presented) The rhodium(I)-catalyzed methylenation of ketones using trimethylsilyldiazomethane proceeds to give the corresponding alkenes in good yields (60-97%). The use of an excess of 2-propanol and 1,4-dioxane as a solvent were instr
- Lebel, Helene,Guay, Danielle,Paquet, Valerie,Huard, Kim
-
p. 3047 - 3050
(2007/10/03)
-
- Successive carbon-carbon bond formation by sequential generation of radical and anionic species with manganese and catalytic amounts of PbCl2 and Me3SiCl
-
Three-component coupling reactions of iodoalkanes, α,β-unsaturated nitriles (or esters), and carbonyl compounds are achieved in good to excellent yields with a moderate reducing system derived from manganese metal and a catalytic amount of PbCl2 and Me3SiCl. Although the role of PbCl2 is unclear, addition of a catalytic amount of the salt is essential for reducing the iodoalkane. The reaction proceeds with primary, secondary, and tertiary iodoalkanes. Both acrylonitrile and acrylic esters can be employed as activated olefins, while the reaction with an alkyl vinyl ketone gives a complex mixture. Ketones and aldehydes can be used as the third component and the diastereoselectivity of the anionic addition is approximately 1: 1-2: 1 ratio. By using the heterogenerative process, i.e., successive 1,4-addition by radical and anionic internal addition, cyclopropanation of electron- deficient olefins is achieved with chloroiodomethane, manganese, PbCl2, Me3SiCl, and DMAP.
- Takai, Kazuhiko,Ueda, Takashi,Ikeda, Norihiko,Ishiyama, Takaya,Matsushita, Hiroshi
-
p. 347 - 353
(2007/10/03)
-
- Synthesis of a C-9 to C-18 building block of the phenalamides
-
In the context of a synthesis of phenalamide A2, the C-9 to C-18 building block 6 was synthesized. The stereogenic centers were generated by alkylation of an Evans oxazolidinone 12 and by a crotylboration reaction using the enantiomerically pure (E)-α-chlorocrotylboronate (4).
- Hoffmann, Reinhard W.,Haeberlin, Eckart,Rohde, Thorsten
-
p. 207 - 212
(2007/10/03)
-
- Highly chemoselective rhodium-catalyzed methylenation of fluorine-containing ketones.
-
[reaction: see text] The rhodium(I)-catalyzed methylenation of functionalized fluorinated ketones using trimethylsilyldiazomethane proceeds to give the corresponding fluoromethylalkenes in good yields (61-90%). Remarkable chemoselectivity was observed for
- Lebel, Helene,Paquet, Valerie
-
p. 1671 - 1674
(2007/10/03)
-
- Novel Preparation of α,β-Unsaturated Aldehydes. Benzeneselenolate Promotes Elimination of HBr from α-Bromoacetals
-
Acetalization, α-bromination, nucleophilic phenylselenenylation, oxidative elimination/hydrolysis was investigated as a novel protocol for the α,β-dehydrogenation of aldehydes. Treatment of acetals with bromine in methylene chloride afforded the corresponding α-bromoacetals in 80-90% yields. Nucleophilic phenylselenenylation was then conveniently effected by treatment with benzenese-lenolate generated in situ in dimethyl sulfoxide from diphenyl diselenide, hydrazine and potassium carbonate. Unbranched α-bromoacetals cleanly afforded substitution products whereas β- and γ-branched ones gave substantial amounts of α,β-unsaturated acetals via formal loss of hydrogen bromide. Oxidative elimination/hydrolysis of these mixtures afforded α,β-unsaturated aldehydes in 50-80% overall yields. In the case of tertiary α-bromoacetals, treatment with benzeneselenolate afforded only dehydrobromination products as mixtures of isomers. The presence of at least a catalytic amount of the organoselenium reagent was found to be crucial for olefin formation. A SET-mechanism, involving benzeneselenolate-induced electron transfer to the halide, loss of bromide ion, and hydrogen atom or proton/electron was proposed for the benzenselenolate-promoted elimination reaction. Experiments designed to trap carbon-centered radicals in intramolecular cyclization or ring-opening reactions failed to provide any evidence for free-radical intermediates.
- Vasil'ev, Andrei,Engman, Lars
-
p. 2151 - 2162
(2007/10/03)
-
- Titanocene(II)-promoted desulfurizative tertiary alkylation of 1,3- bis(phenylthio)alk-1-enes and β,γ-unsaturated thioacetals
-
The desulfurization of 1,3-bis(phenylthio)alk-1-enes with the low valent titanium species Cp2Ti[P(OEt)3]2 and subsequent reaction with tert-alkyl chlorides gave the terminal olefins regioselectively. The similar reactions
- Takeda, Takeshi,Nozaki, Naoki,Saeki, Naoko,Fujiwara, Tooru
-
p. 5353 - 5356
(2007/10/03)
-
- Organometallic-type reactions in aqueous media. Wurtz-coupling of alkyl halides with manganese/cupric chloride
-
Homo-coupling of alkyl halides in aqueous media can be mediated by manganese/cupric chloride to give the dimerisation products in good yield. Cross-coupling can also be controlled to give the desired product.
- Ma, Jihai,Chan, Tak-Hang
-
p. 2499 - 2502
(2007/10/03)
-
- Conjugative interaction in styrenes
-
Conjugative interactions of the carbon-carbon double bond are fundamental in organic chemistry. In this work, equilibria are established among conjugated and unconjugated isomers of two β-substituted styrenes, 1-phenylbut-1-ene and 1-phenyl-3-methylbut-1-ene, and one α,β-disubstituted styrene, 2-phenyl-5-methylhex-2-ene, over a range of temperatures (the van't Hoff method) in hexamethylphosphoric triamide and potassium tert-butoxide. From the trans styrenes of the first two sets, an enthalpy of conjugative interaction of phenyl vis-a-vis alkyl (ΔΔH(ConjInter/Alk)) = -2.5 ± 0.2 kcal/mol [-5.1 kcal/mol defined as phenyl vis-a-vis hydrogen (ΔΔH(ConjInter/H))] is observed, while the cis styrenes reveal an attenuated ΔΔH(ConjInter/Alk) of -1.1 kcal/mol (ΔΔH(ConjInter/H)) = -2.7 kcal/ mol). The α-methyl group in the third set also leads to a reduced conjugative interaction. Entropy plays an important role in determining positions of equilibrium. Free energies of conjugation are reported for several sterically hindered o-methyl-substituted styrenes.
- Von Doering,Benkhoff, Johannes,Carleton, Peter Smart,Pagnotta, Marco
-
p. 10947 - 10955
(2007/10/03)
-
- Photolysis of Alkyl Aryl Sulfoxides: α-Cleavage, Hydrogen Abstraction, and Racemization
-
The photochemistry of a series of alkyl aryl sulfoxides is described. The initial event of the photolysis process is homolytic cleavage to form sulfinyl/alkyl radical pairs. The radical pair partitions between recombination to starting material, formation of sulfenic esters, disproportionation to an olefin and benzenesulfenic acid, and formation of typical radical escape products. The quantum yield for conversion depends on the structure or the reactivity of the alkyl radical, with the sequence benzyl > tertiary alkyl > secondary alkyl > primary alkyl > (di)aryl. The high racemization efficiency of some aryl primary-alkyl sulfoxides suggests that another nonradical pathway for the photoracemization process may exist. Product analysis does not support any hydrogen abstraction pathways.
- Guo, Yushen,Jenks, William S.
-
p. 857 - 864
(2007/10/03)
-
- A simple and convenient synthesis of alkyl azides under mild conditions
-
Various primary and secondary alkyl azides have been synthesized in high yields by the fluoride anion induced S(N)2 substitution reactions of the corresponding alkyl halides, phosphates, or tosylates and trimethylsilyl azide.
- Ito,Koyakumaru,Ohta,Takaya
-
p. 376 - 378
(2007/10/02)
-
- A Novel Catalytic Effect of Lead on the Reduction of a Zinc Carbenoid with Zinc Metal Leading to a Geminal Dizinc Compound. Acceleration of the Wittig-Type Olefination with the RCHX2-TiCl4-Zn Systems by Addition of Lead
-
A catalytic amount of lead promotes further reduction of zinc carbenoid (ICH2ZnI) with zinc in THF to give a geminal dizinc compound (CH2(ZnI)2), which is a key intermediate for the methylenation of carbonyl compounds with a CH2I2, zinc, and TiCl4 system.
- Takai, Kazuhiko,Kakiuchi, Tadahiro,Kataoka, Yasutaka,Utimoto, Kiitiro
-
p. 2668 - 2670
(2007/10/02)
-
- Direct Conversion of Alcohols into Thiols
-
A simple one-pot reaction between alcohols and 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide (Lawesson's reagent, LR) affords the corresponding thiols, accompanied by dehydration products, alkenes.Treatment of acyclic 1,4-diols with LR gives the 1,3-dienes. o-(Dihydroxymethyl)benzene derivatives yield the 1,3-dihydrobenzothiophenes when treated with LR.
- Nishio, Takehiko
-
p. 1113 - 1118
(2007/10/02)
-
- Palladium Catalyzed Stereoselective Hydrodehalogenation of Alkenyl Halides with Tributyltin Hydride
-
The reduction of alkenyl halides with tributyltin hydride in the presence of a catalytic amount of tetrakis(triphenylphosphine)palladium has been studied.Alkenyl iodides reacted easily with tributyltin hydride at 25 deg C to give the corresponding hydrocarbons stereoselectively.However, the reaction of alkenyl bromides were sluggish at 25 deg C and needed heating at 75 deg C to complete.
- Taniguchi, Masahiko,Takeyama, Yoshihiro,Fugami, Keigo,Oshima, Koichiro,Utimoto, Kiitiro
-
p. 2593 - 2595
(2007/10/02)
-
- The action of sodium hydrogen telluride on olefins
-
The action of sodium hydrogen telluride, NaTeH, on non electrophilic carbon-arbon double bonds has been investigated.The reaction is found to be very sensitive to the substituents on the ethylenic linkage. Whereas phenyl conjugated olefins are reduced to alkylbenzenes,the reagent adds to isolated mono and disubstituted double bonds leading to organotellurium derivatives and with gem-disubstituted ones it leads to a mixture of reduction and addition products. These results are interpreted in terms of a radical pair mechanism involving hydrogen atom transfer from hydrogen telluride,HTe- to the double bond.
- Barton, Derek H. R.,Bohe, Luis,Lusinchi, Xavier
-
p. 5273 - 5284
(2007/10/02)
-