- Enantioselective synthesis of 3-substituted dihydrobenzofurans through iridium-catalyzed intramolecular hydroarylation
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Intramolecular hydroarylationviaC-H activation is one of the most powerful methods to synthesize carbo- and heterocyclic compounds, whereas we still have room for developing a highly enantioselective variant of the reaction. Here we describe Ir-catalyzed enantioselective intramolecular hydroarylation ofm-allyloxyphenyl ketones. The enantioselective cyclization was efficiently catalyzed by a cationic iridium complex coordinated with a conventional chiral bisphosphine ligand to give benzofurans in high yields with high enantioselectivity. A carbonyl group of ketones functioned as an effective directing group for the C-H activation. In terms of synthetic utility, we also achieved one-pot synthesis of chiral 3-substituted dihydrobenzofurans from readily available allylic carbonates andm-hydroxyacetophenonesviasequential Pd-catalyzed allylic substitution and Ir-catalyzed intramolecular hydroarylation.
- Nishimura, Takahiro,Sakamoto, Kana
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supporting information
p. 684 - 690
(2021/02/06)
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- Highly selective hydrosilylation of equilibrating allylic azides
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The Pt-catalyzed hydrosilylation of equilibrating allylic azides is reported. The reaction provides only one out of four possible hydrosilylation products in good yields and with very high chemoselectivity (alk-1-enevs.alk-2-ene), regioselectivity (linearvs.branched), and excellent functional group tolerance.
- Liu, Ruzhang,Liu, Yongmei,Wang, Juan,Wei, Zhen,Xue, Huaiguo
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supporting information
p. 5038 - 5041
(2020/05/18)
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- Synthesis method of 3-azidopropylsilane
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The invention discloses a synthetic method of 3-azidopropylsilane, wherein the method comprises the steps: firstly, allyl azide is synthesized by allyl bromide, and because the allyl azide is easy togenerate [3,3] rearrangement reaction at room temperatur
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Paragraph 0039; 0040
(2020/06/05)
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- In Situ Generated Gold Nanoparticles on Active Carbon as Reusable Highly Efficient Catalysts for a Csp3 ?Csp3 Stille Coupling
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Gold nanoparticle catalysts are important in many industrial production processes. Nevertheless, for traditional Csp2-Csp2 cross-coupling reactions they have been rarely used and Pd catalysts usually give a superior performance. Herein we report that in situ formed gold metal nanoparticles are highly active catalysts for the cross coupling of allylstannanes and activated alkylbromides to form Csp3-Csp3 bonds. Turnover numbers up to 29 000 could be achieved in the presence of active carbon as solid support, which allowed for convenient catalyst recovery and reuse. The present study is a rare case where a gold metal catalyst is superior to Pd catalysts in a cross-coupling reaction of an organic halide and an organometallic reagent.
- Holz, Julia,Pfeffer, Camilla,Zuo, Hualiang,Beierlein, Dennis,Richter, Gunther,Klemm, Elias,Peters, René
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supporting information
p. 10330 - 10334
(2019/06/27)
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- BOTPPI, a new Wittig salt for the synthesis of 12-(S)-hydroxy- eicosatetraenoic acid [12-(S)-HETE]
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An efficient route to (Z)-(8-benzyloxy-8-oxooct-3-en-1-yl) triphenylphosphonium iodide, or BOTPPI, is disclosed, complete with full experimental details, NMR spectra, and HRMS data. BOTPPI serves as a surrogate for (Z)-(8-methoxy-8-oxooct-3-en-1-yl)triphe
- Christiansen, Michael A.,Andrus, Merritt B.
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supporting information; experimental part
p. 4805 - 4808
(2012/09/22)
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- A catalytic asymmetric chlorocyclization of unsaturated amides
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The asymmetric chlorocyclization of unsaturated amides catalyzed by (DHQD)2PHAL yields oxazoline and dihydrooxazine derivatives (see scheme). The reaction is operationally simple and employs 1-2 mol % of the commercially available (DHQD)2PHAL (hydroquinidine 1,4-phthalazinediyl diether) catalyst. Different substitution patterns of the olefin as well as aromatic and aliphatic olefin substituents are well tolerated. DCDPH=N,N-dichloro-5,5-diphenylhydantoin. Copyright
- Jaganathan, Arvind,Garzan, Atefeh,Whitehead, Daniel C.,Staples, Richard J.,Borhan, Babak
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supporting information; scheme or table
p. 2593 - 2596
(2011/05/02)
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- Factors influencing the autoxidation of fatty acids: Effect of olefin geometry of the nonconjugated diene
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Autoxidations of cis,cis, cis,trans, and trans,trans nonconjugated octadecadienoates and pentadecadienes were carried out in the presence of α-tocopherol to investigate the effect of olefin geometry on this oxidation process and provide insight into the factors that influence the autoxidation of fatty acids. We have found that as the trans character of the diene increases, the amount of O2 trapping at the central (bis-allylic) position of the pentadienyl radical also increases. In addition, the rate constant for β-fragmentation (kβ ≈ 10 6 s-1) of the bis-allylic peroxyl radical decreased on going from the cis,cis to the trans,trans diene. We have also found that for the cis,trans nonconjugated dienes, there is a preference for trapping of the pentadienyl radical by O2 at the transoid end, generating the cis,trans conjugated hydroperoxide as the major product.
- Tallman, Keri A.,Roschek Jr., Bill,Porter, Ned A.
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p. 9240 - 9247
(2007/10/03)
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- Large-scale preparation of (9Z,12E)-[1-13C]-octadeca-9,12-dienoic acid, (9Z,12Z,15E)-[1-13C]-octadeca-9,12,15-trienoic acid and their [1-13C] all-cis isomers
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Several grams of labelled trans linoleic and linolenic acids with high chemical and isomeric purities (>97%) have been prepared for human metabolism studies. A total of 12.5 g of (9Z,12E)-[1-13C]-octadeca-9,12-dienoic acid and 6.3 g of (9Z,12Z,15E)-[1-13C]-octadeca-9,12,15-trienoic acid were obtained in, respectively, seven steps (7.8% overall yield) and 11 steps (7% overall yield) from 7-bromo-heptan-1-ol. The trans bromo precursors used for the labelling were synthesised by using copper-catalysed couplings. The trans fatty acids were then obtained via the nitrile derivatives. A total of 23.5 g of (9Z,12Z)-[1-13C]-octadeca-9,12-dienoic acid and 10.4 g of (9Z,12Z,15Z)-[1-13C]-octadeca-9,12,15-trienoic acid were prepared in five steps in, respectively, 32 and 18% overall yield. Large quantities of bromo and chloro precursors were synthesised from the commercially available acid according to Barton's procedure. In all cases, the main impurities (>0.5%) of each labelled fatty acid have been characterised. Copyright (C) 2000 Elsevier Science Ireland Ltd.
- Loreau,Maret,Poullain,Chardigny,Sebedio,Beaufrere,Noel
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- 5-F2t-isoprostane, a human hormone?
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Syntheses of the four enantiomerically pure diastereomers of 5-F2t-isoprostane (5-8) are described. The key step is the lipase-catalyzed chemo-enzymatic resolution of the racemic diol 40 to give the mono-acetates 41 and 42. The enantiomerically
- Taber, Douglass F.,Kanai, Kazuo,Pina, Richard
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p. 7773 - 7777
(2007/10/03)
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- Bromide assisted addition of hydrogen bromide to alkynes and allenes
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The addition of 0.1 M quaternary ammonium bromide to a solution of 20% trifluoroacetic acid in methylene chloride causes a large rate increase in the reaction of non-conjugated alkynes. The initial vinyl bromide product reacts further to provide a mixture of isomeric vinyl bromides and dibromides. At high salt concentrations however, the secondary reactions are prevented and only the initial vinyl bromide is found. In contrast to the corresponding addition to alkenes, the predominant mechanism is proposed to involve a one-step, concerted, nucleophilic attack by halide ion upon an acid-alkyne π-complex which produces the vinyl halide directly. A minor path involving syn addition is also seen. At all salt concentrations, allenes produce significant amounts of rearrangement products suggesting the significant involvement of a cationic mechanism.
- Weiss, Hilton M.,Touchette, Kim M.
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p. 1523 - 1528
(2007/10/03)
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- EXO- AND ENDOHORMONES, XVI SYNTHESIS OF (4E, 7Z)-4,7-TRIDECADIEN 1-YL ACETATE, THE SEX PHEROMONE FOR THE LEAFMINER LITHOCOLLETIS CORYLIFOLIELLA
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The synthesis of the sex pheromone of the leafminer moth, Lithocolletis corylifoliella, (4E, 7Z)-4,7-tridecadien-1-yl acetate, was based on a C5+C8 scheme.The coupling reaction took place between the Grignard reagent of 4-pentin-1-1-oic acid and 1-bromo-2Z-octene.Propargylic alcohol was used as a starting material in order to obtain the two synthons.
- Gocan, Alexandra,Gansca, Lucia,Oprean, Ioan
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p. 253 - 258
(2007/10/03)
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- Syntheses of cerulenin and its analogs. I. Cerulenin and its analogs with modified side chain
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Optically active cerulenin 1, a potent inhibitor of fatty acid synthetase, was prepared via the condensation of the epoxy aldehyde 8 and the alkenyl lithium 16. In order to evaluate the effects of (E,E)-1,4-double bonds of the cerulenin side chain on the interaction with the enzyme, a series of optically active cerulenin analogs 32a-i with modified side chains and tetrahydrocerulenin 3 were synthesized by similar procedures.
- Morisaki,Funabashi,Furukawa,Shimazawa,Kanematsu,Ando,Okuda,Iwasaki
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p. 2945 - 2953
(2007/10/02)
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- DIRECT CONVERSION OF TETRAHYDROPYRANYLATED ALCOHOLS TO THE CORRESPONDING BROMIDES
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Various tetrahydro-2 pyranyl protected alcohols are converted into the corresponding bromides by PPh3/CBr4, with inversion of configuration, and high in yield.
- Wagner, A.,Heitz, M.-P.,Mioskowski, C.
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p. 557 - 558
(2007/10/02)
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- PREPARATIVE SYNTHESIS OF TOSYLATES OF UNSATURATED ALCOHOLS AND UNSATURATED BROMIDES UNDER PHASE TRANSFER CONDITIONS
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A preparative synthetic method has been developed for tosylates of unsaturated alcohols and their conversion to bromides under phase transfer conditions in the case of alkyn-1-ols, E- and Z-alken-1-ols, 3-methyl-3-buten-1-ol and cyclopropylmethanol.
- Ishchenko, R. I..,Kovalev, B. G.,Khusid, A. Kh.
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p. 1076 - 1078
(2007/10/02)
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- The Preparation of Some Octenyl Sulfides from Oct-1-en-3-ol and Oct-2-en-1-ol
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(E)- and (Z)-1-(Phenylthio)oct-2-ene, (E)-1-(methylthio)- and 1-(t-butylthio)-oct-2-ene, S- N,N-dimethylthiocarbamate, S- N,N-dimethylthiocarbamate, (E)-(oct-2-enylthio)benzothiazole, and S- N,N,N',N'-tetramethylphosphorodiamidothioate have been prepared by nucleophilic substitution reactions and - and -sigmatropic shifts involving intermediates prepared from oct-1-en-3-ol and (E)- and (Z)-oct-2-en-1-ol.
- Binns, Malcolm R.,Haynes, Richard K.,Lambert, Dale E.,Schober, Paul A.,Turner, Susan G.
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p. 281 - 290
(2007/10/02)
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- ALLYLATION OF GRIGNARD REAGENTS: ITS APPLICATION FOR THE SYNTHESIS OF (4E,7Z)-4,7-TRIDECADIENYL ACETATE, A SEX PHEROMONE OF POTATO TUBERWORM MOTH
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Alkylmagnesium halides have been found to react with (Z)-4-benzyloxy-1-chloro-2-butene in presence of HMPA to produce a rearranged product 3-alkyl-4-benzyloxy-1-butene, while the absence of HMPA a normal product (Z)-1-alkyl-4-benzyloxy-2-butene resulted as the predominant product.Latter product has been utilized for the synthesis of (4E,7Z)-4,7-tridecadienyl acetate, a sex pheromone of potato tuberworm moth.
- Yadav, J. S.,Reddy, P. Satyanarayana
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p. 1119 - 1132
(2007/10/02)
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- Total Synthesis of (+/-)-12-Hydroxy-5(Z),8(Z),10(E),14(Z)-eicosatetraenoic Acid (12-HETE)
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A total synthesis of 12-HETE is reported which incorporates an oxidative cleavage of an appropriately substituted furan to provide a functionalized trans-allylhydroxy fragment which is subsequently elaborated in an operationally simple manner affording a practical preparation of 12-HETE.
- Gunn, Bruce P.,Brooks, Dee W.
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p. 4417 - 4418
(2007/10/02)
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- Synthesis of Heptadeca-1,8Z,11Z-triene
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The bromide (III), obtained from oct-2Z-en-1-ol (II) by treatment with PBr3/pyridine, reacts smoothly with 3-(tetrahydro-2-pyranyloxy)propynylmagnesium bromide to give IV which loses the protective pyranyl moiety when reacted with PTS/methanol to yield the alcohol (V).Catalytic hydrogenation of V in the presence of Lindlar's catalyst affords the dienol (VI) which is converted into the corresponding mesylate (VII) on reaction with MsCl/TEA.Coupling of VII with hex-1-enylmagnesium bromide in THF/HMPA at 0 deg C provides the title compound (I).
- Vig, O. P.,Sharma, M. L.,Kumari, Sarla,Rani, Veena
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p. 769 - 770
(2007/10/02)
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- A Convenient Synthesis of (Z)-5-Undecen-2-one, Sex Pheromone from the Pedal Gland of Bontebok
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Oct-2-yn-1-ol (II) on catalytic hydrogenation over 5percent Lindlar's catalyst yields (Z)-2-octen-1-ol (III) which is transformed into 1-bromo-2(Z)-octene (IV) by treatment with PBr3.Alkylation of α-lithioacetone dimethylhydrazone with IV in THF at -78 deg C followed by hydrolysis of the resulting hydrazone with NaIO4 at pH 7 results in formation of the title compound (I).
- Trehan, I. R.,Kad, G. L.,Varma, Neena,Singh, Labh
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p. 1273 - 1274
(2007/10/02)
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- A New Synthesis of (Z)-Heneicos-6-en-11-one, Sex Pheromone of Douglas Fir Lepidoptera Orgyia pseudotsugata
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2-Octyn-1-ol (II) on hydrogenation over Lindlar's catalyst provides (Z)-2-octen-1-ol (III).Conversion of III into the corresponding bromide (IV) with PBr3 and subsequent alkylation of ethyl monosodiomalonate with IV in benzene/DMF mixture gives the diester (V) in high yield.Removal of one carbethoxy group of (V) on heating with NaCl/H2O in DMSO affords ethyl 4(Z)-decenoate (VI) which on LAH reduction yields the carbinol (VII).Treatment of VII with PBr3 in dry ether furnishes the bromide (VIII) which easily forms Grignard reagent (IX) with dry Mg turnings in anhyd.THF.The reagent (IX) on reaction with undecanal furnishes (Z)-heneicos-6-en-11-ol (X).Oxidation of X with Corey's reagent provides (Z)-heneicos-6-en-11-one (I).
- Vig, O. P.,Sharma, M. L.,Verma, N. K.,Malik, Neera
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p. 950 - 951
(2007/10/02)
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- REGIOSPECIFIC ALLYLATION OF SULFUR SUBSTITUTED ACTIVE METHYLENE COMPOUNDS WITH ALLYLIC BROMIDES
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Allylation of sulfur substituted active methylene compounds such as RSCH2Y with allylic bromides in the presence of bases gives a mixture of the SN2-product and the apparent SN2'-product.The former product is selectively obtained in alkylation in a nonpolar solvent.Synthetic utility of this regiospecific allylation is demonstrated in the simple synthesis of pellitorine.
- Ono, Noboru,Miyake, Hideyoshi,Tanabe, Yo,Tanaka, Kazuhiko,Kaji, Aritsune
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p. 1365 - 1368
(2007/10/02)
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