- A simple method for the displacement of bromine by fluorine at tertiary benzylic or non-classical secondary sites
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Iodine fluoride or, being its operational equivalent, the mixture of N-iodosuccinimide and triethylamine tris(hydrogen fluoride) reacts with tertiary and benzylic bromoalkanes to afford the respective fluoroalkanes in moderate-to-excellent yields. In contrast, primary bromoalkanes are virtually inert under identical conditions. Secondary bromoalkanes do not react either unless the heterolytically generated cationic intermediates benefit from non-classical resonance stabilization.
- Leroux, Frédéric,Garamszegi, László,Schlosser, Manfred
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Read Online
- Total synthesis of unsaturated imine venom alkaloids of Costa Rican ant by way of Schmidt reaction via allyl/pentadienyl cations
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Total synthesis of α,β-, and α,β,γ,δ-unsaturated imine ant venom alkaloids is described. The labile two conjugated imine alkaloids were synthesized by late stage intramolecular Schmidt reaction via allyl and pentadienyl cation intermediates.
- Zhang, Huan,Hayashi, Kyohei,Tanimoto, Hiroki,Morimoto, Tsumoru,Nishiyama, Yasuhiro,Kakiuchi, Kiyomi
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Read Online
- CREATINE PRODRUGS, COMPOSITIONS AND METHODS OF USE THEREOF
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The present disclosure provides creatine prodrug analogs and their compositions useful for the treatment of creatine deficiencies.
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Paragraph 00651; 00653
(2019/06/17)
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- Bismuth chloride mediated allylation of carbonyl compounds in aqueous media: A mechanistic investigation
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The bismuth chloride mediated, aluminum promoted aqueous Barbier type coupling of allyl unit with carbonyl compounds which gives the corresponding homoallyl alcohol is studied. The transient in situ generated allylbismuth(III) bromide intermediate was stu
- Jadhav,Pardeshi
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p. 4948 - 4952
(2014/12/11)
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- Efficient synthesis of α,β-unsaturated alkylimines performed with allyl cations and azides: Application to the synthesis of an ant venom alkaloid
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An efficient synthesis of α,β-unsaturated alkylimines at low temperature using azides has been developed. Carbocations generated from allyl alcohols helped achieve a rapid conversion under mild conditions with azides to afford reactive α,β-unsaturated imines. Hydroxy or alkoxy groups are essential for these transformations, and utilizing readily accessible allyl alcohols gave a wide extension of substrates. The efficiency of this novel method is demonstrated in the total synthesis of an iminium ant venom alkaloid.
- Hayashi, Kyohei,Tanimoto, Hiroki,Zhang, Huan,Morimoto, Tsumoru,Nishiyama, Yasuhiro,Kakiuchi, Kiyomi
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supporting information
p. 5728 - 5731
(2013/01/15)
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- Indium-mediated synthesis of homoallyl alcohols in the aqueous phase
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The indium-mediated Barbier-type allylation reaction of aldehydes with allyl bromide, which gives corresponding homoallyl alcohols, was investigated. The reaction medium and the effects of substituents were discussed in detail. The results showed that var
- Du, Zhengyin,Li, Yanchun,Wang, Fen,Zhou, Wanwei,Wang, Jin-Xian
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experimental part
p. 1664 - 1671
(2011/06/20)
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- Indium-mediated Barbier-type allylation reaction in PEG400 and PEG400/H2O
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A green method for the allylation of aldehydes with allyl bromide mediated by indium in polyethylene glycol 400 (PEG400) and PEG400/H2O is described. Aldehydes with different substituents afforded the corresponding homoallylic alcohols in good to excellen
- Du, Zhengyin,Wang, Fen,Zhou, Wanwei,Wang, Jin-Xian
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experimental part
p. 475 - 477
(2010/12/25)
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- Substituted 3-hydroxy-delta-lactones from epoxides
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Catalysts and methods for the carbonylation of epoxides to substituted 3-hydroxy-δ-lactones and β-lactones are disclosed.
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Page/Page column 19-20
(2010/06/19)
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- Synthesis and structure of air-stable Lewis acidic binuclear complex of zirconocene pentafluorophenylsulfonate and its catalytic application in the allylation of carbonyl compounds with tetraallyltin
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Air-stable Lewis acidic μ2-hydroxy bridged binuclear complex of zirconocene pentafluorophenylsulfonate was successfully synthesized and found to show high catalytic efficiency in chemoselective allylation of carbonyl compounds with tetraallylti
- Qiu, Renhua,Xu, Xinhua,Li, Yinhui,Zhang, Guoping,Shao, Lingling,An, Delie,Yin, Shuangfeng
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supporting information; experimental part
p. 1679 - 1681
(2009/08/08)
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- Mild and efficient allylation of aldehydes with allyltributylstannane promoted by MgI2·(OEt)n etherate
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Allylation of aldehydes with allyltributylstannane was promoted in the presence of MgI2·(OEt)n to give homoallylic alcohols. The iodide anion and a noncoordinating reaction medium (CH 2Cl2) are the key features
- Zhang, Xingxian
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- Carbonylation of epoxides to substituted 3-hydroxy-α-lactones
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Substituted 3-hydroxy-δ-lactones (3HLs) are valuable intermediates in the synthesis of pharmaceuticals and other biologically active natural products. Herein we report the first example of the catalytic carbonylation of substituted homoglycidols to 3HLs using HCo(CO)4. Upon optimization of the catalyst and reaction conditions, a functionally diverse set of 3HLs was prepared. Mechanistic insight was gained by observation of the carbonyiation reaction using in situ IR spectroscopy, and we propose a mechanism that is consistent with previously studied epoxide carbonyiation systems.
- Kramer, John W.,Joh, Daniel Y.,Coates, Geoffrey W.
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p. 5581 - 5583
(2008/09/17)
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- Novel and efficient method for the allylation of carbonyl compounds and imines using triallylaluminum
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This is the first report of the use of triallylaluminum as a reagent for the allylation of carbonyl compounds and imines. The allylation of ketimines without additional metal catalyst is known so far only in the case of the Grignard reagent. Triallylaluminum is a useful alternative to provide the homoallylic amines in excellent yield upon addition to aldimines and ketimines. The significant reactivity of this reagent was confirmed by its reaction with a sterically rigid ketone such as adamantanone to provide 1-adamantyl-3-buten-1-ol in 98% yield. The chemoselectivity of triallyl-aluminum was demonstrated by using different ketoesters. It is noteworthy that triallylaluminum is prepared from allyl bromide and aluminum metal, and not from a Grignard reagent, and that the procedure is operationally simple, leading to good to excellent product yields.
- Shen, Kao-Hsien,Yao, Ching-Fa
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p. 3980 - 3983
(2007/10/03)
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- Stereoselective cyclization reactions of IBX-generated alkoxyamidyl radicals
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In this paper, a method for the generation of alkoxyamidyl radicals is presented. These N-centered radicals can efficiently be formed starting from the corresponding acylated alkoxyamines using IBX as an oxidant. Stereoselective 5-exo and 6-exo reactions with these N-heteroatom-centered radicals leading to isoxazolidines and [1,2]oxazinanes are discussed. The N-O bond in the heterocycles can readily be cleaved with SmI2 to provide N-acylated 1,3-amino alcohols.
- Janza, Birgit,Studer, Armido
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p. 6991 - 6994
(2007/10/03)
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- A novel gallium/samarium-mediated coupling of epoxides with allyl halides in aqueous media and synthesis of homoallylic alcohols
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A mild and efficient protocol for the coupling of various substituted epoxides 1 with allylgallium reagent generated in situ in a Bu 4NBr-DMF-H2O system have been developed. The coupling is also found to be equally effective when samarium is used in lieu of gallium and the corresponding homoallylic alcohols 2 were obtained in almost comparable yields. Copyright
- Gohain, Mukut,Prajapati, Dipak
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- Indium-catalyzed Barbier allylation reaction
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Barbier allylation reaction of carbonyl compounds with allyl bromide was investigated using a catalytic amount of indium (0), indium (I) or indium (III) salts in the presence of a reducer and chlorotrimethylsilane (TMSCl). The Mn/TMSCl couple turned out to be the most efficient system to regenerate active indium in the allylation reaction of various carbonyl compounds including α- and β-oxygenated aldehydes.
- Augé, Jacques,Lubin-Germain, Nadège,Marque, Sylvain,Seghrouchni, Latifa
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- Allylation of aldehydes catalyzed by zeolites under liquid phase
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Dealuminated zeolite-Y exchanged with rare earth metals (RE-Y) is found to catalyze the allylation of different aldehydes using allyltrimethylsilane to afford the corresponding allylic compounds in moderate to good yields by refluxing in nitromethane.
- Sasidharan,Tatsumi, Takashi
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p. 624 - 625
(2007/10/03)
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- Ceric(IV) ammonium nitrate: A novel reagent for the synthesis of homoallyl alcohols
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A rapid and highly efficient method has been developed for the allylation of aldehydes with allyltributylstannane using a catalytic amount of eerie ammonium nitrate in acetonitrile under mild and neutral conditions to afford the corresponding homoallyl al
- Yadav,Reddy,Krishna,Sadasiv,Chary, Ch. Janardhana
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p. 248 - 249
(2007/10/03)
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- Iodine-catalysed allylation of aldehydes with allyltrimethylsilane
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Iodine efficiently catalyses the allylation of both aromatic and aliphatic aldehydes with allyltrimethylsilane in acetonitrile at 0°C to afford the corresponding homoallyl alcohols in high yields in a short reaction time.
- Yadav,Chand, Pratap K.,Anjaneyulu
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p. 3783 - 3784
(2007/10/03)
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- Synthesis and stereochemistry of some bicyclic γ-lactones from parasitic wasps (Hymenoptera: Braconidae). Utility of hydrolytic kinetic resolution of epoxides and palladium(II)-catalyzed hydroxycyclization-carbonylation-lactonization of ene-diols
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A palladium(II)-catalyzed hydroxycyclization-carbonylation-lactonization sequence with appropriate pent-4-ene-1,3-diols provides efficient access to the bicyclic γ-lactones, 5-n-butyl- and 5-n-hexyltetrahydrofuro-[3,2-b]furan-2(3H)-ones (3) and (4), respectively, in both racemic and enantiomeric forms. Some of the substrate pent-4-ene-1,3-diols of high enantiomeric excess (ee) have been derived from racemic terminal epoxides by hydrolytic kinetic resolution (HKR) using cobalt (III) - salen complexes. (9Z,12R)-(+)-Ricinoleic acid also serves as a "chiral pool" source of other pent-4-ene-1,3-diols. These syntheses and enantioselective gas chromatography confirm the structures and absolute stereochemistry of the lactones in some species of parasitic wasps (Hymenoptera: Braconidae). The highly abundant 5-n-hexyltetrahydrofuro-[3,2-b]furan-2(3H)-one (4) in Diachasmimorpha kraussii and D. longicaudata is of high ee (>99%) with (3aR,5R,6aR) stereochemistry.
- Paddon-Jones,McErlean,Hayes,Moore,Konig,Kitching
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p. 7487 - 7495
(2007/10/03)
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- ROMPgel supported allylboronate: A purification-free method for the preparation of homoallylic alcohols
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Allylboration of various aldehydes was carried out by a ROMPgel supported allylboronate. Filtration and evaporation gave the corresponding homoallylic alcohols in high yield and purity (>95%).
- Arnauld, Thomas,Barrett, Anthony G.M,Seifried, Robert
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p. 7899 - 7901
(2007/10/03)
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- Peroxycarbenium-mediated C-C bond formation: Applications to the synthesis of hydroperoxides and peroxides
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The Lewis acid-mediated reaction of alkene nucleophiles with peroxyacetals provides an effective route for the synthesis of homologated peroxides and hydroperoxides. In the presence of Lewis acids such as TiCl4, SnCl4, and trimethylsilyl triflate, peroxyacetals and peroxyketals undergo reaction with allyltrimethylsilane, silyl enol ethers, and silyl ketene acetals to afford homoallyl peroxides, 3-peroxyketones, and 3-peroxyalkanoates, respectively. Reactions of peroxyacetals are Lewis acid dependent; TiCl4 promotes formation of ethers while SnCl4 and trimethylsilyl triflate promote formation of peroxides. Lewis acid-promoted reactions of silylated hydroperoxyacetals furnish silylated hydroperoxides, which can be deprotected to homologated hydroperoxides. Hydroperoxyketals undergo Lewis acid-mediated allylation to furnish 1,2-dioxolanes via attack of hydroperoxide on the intermediate carbocation. Lewis acid-mediated cyclization of unsaturated peroxyacetals furnishes 1,2-dioxanes, 1,2-dioxepanes, and 1,2-dioxacanes through 6-endo/exo, 7-endo/endo, and 8-endo/endo pathways. The corresponding reactions involving 6-endo/endo and 5-endo/exo pathways were unsuccessful.
- Dussault,Lee, In Quen,Lee,Lee,Niu,Schultz,Zope
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p. 8407 - 8414
(2007/10/03)
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- Barbier-type allylation of aldehydes with active metallic antimony
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Highly reactive antimony, prepared by the NaBH4 reduction of SbCl3, induced allylation of aldehydes with allylic bromide in DMF/H2O solvent to give good yields of the corresponding homoallylic alcohols with high regio- and
- Ren, Ping-Da,Jin, Qi-Hui,Yao, Zi-Peng
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p. 2761 - 2767
(2007/10/03)
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- Synthesis and absolute stereochemistry of Hagen's-Gland lactones in some parasitic wasps (Hymenoptera:Braconidae)
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Efficient syntheses and enantioselective gas chromatography have confirmed the structures and established the absolute stcreochemistry of some novel bicyclic lactones (tetrahydrofurofuranones) in species of parasitic wasps (Hymenoptera:Braconidae). The co-occurring γ-lactones, octan-4-olide and dodecan-4-olide, have the (R)-configuation.
- Paddon-Jones, Gregory C.,Moore, Christopher J.,Brecknell, Douglas J.,Koenig, Wilfried A.,Kitching, William
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p. 3479 - 3482
(2007/10/03)
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- Additive effects of ligand activated allylation of aldehydes by allyltrichlorosilane
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The rate of allylation of aldehydes using a combination of allyltrichlorosilane and O-donor ligands can he profoundly accelerated by the addition of a range of simple tetra-n-butylammonium salts. Measured tin values decrease from over 6 hours under define
- Short, Joanne D.,Attenoux, Sandrine,Berrisford, David J.
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p. 2351 - 2354
(2007/10/03)
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- Scandium trifluoromethanesulfonate, a novel catalyst for the addition of allyltrimethylsilane to aldehydes
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Scandium triflate (2-10 mol%) has been found to be a highly efficient catalyst for the addition of allyltrimethylsilane to both aromatic and aliphatic aldehydes.
- Aggarwal, Varinder K.,Vennall, Graham P.
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p. 3745 - 3746
(2007/10/03)
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- Allylic tin(IV)-tin(II) chloride-acetonitrile as a novel system for allylation of carbonyls or imines
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Effective allylation of aldehydes, ketones and imines was accomplished by allylic tributyltins 1 in the presence of SnCl2 in an acetonitrile solution. In this reaction system, Sn(IV)-Sn(II) transmetallation must play a key role, generating the
- Yasuda, Makoto,Sugawa, Yoshihiro,Yamamoto, Akihiro,Shibata, Ikuya,Baba, Akio
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p. 5951 - 5954
(2007/10/03)
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- Concentration effects in chelation controlled reactions
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The diastereoselectivities of addition reactions of allyltrimethylsilane to an α-benzyloxyaldehyde were found to be relatively insensitive to the amount of added TiCl4, and to the absolute concentration of the 1:1 aldehyde/TiCl4 complex. In contrast, diastereoselectivities of similar additions to a structurally related β-benzyloxyaldehyde were highly dependent on these variables.
- Springer,Springer, James B.,DeBoard,Deboard, Julie,Corcoran,Corcoran, Robert C.
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p. 8733 - 8736
(2007/10/02)
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- Super-acid Catalysed Addition of Allylsilanes to Carbonyl Compounds; Synthetic and Mechanistic Aspects
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The addition of allyltrimethylsilane 8 to a variety of aldehydes and one ketone (cyclohexanone) was found to be induced by the super-acid TfOH2(1+)B(OTf)4(1-) (Tf = CF3SO2).In contrast to the analogous Lewis acid catalysed reaction, only catalytic amounts
- Davis, Anthony P.,Jaspars, Marcel
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p. 2111 - 2118
(2007/10/02)
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- Superacid Catalysis of the Addition of Allysilanes to Carbonyl Compounds
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The superacid TfOH2+B(OTf)4- (Tf = CF3SO2) was found to catalyse the addition of trialkylallysilanes to aldehydes and a ketone (the Sakurai reaction) at levels of ca. 0.5 molpercent; the reactions were clean, highly-yielding, and reg
- Davis, Anthony P.,Jaspars, Marcel
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p. 1176 - 1178
(2007/10/02)
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