- Synthesis of C14-Desmethylene Corialactone D and Discovery of Inhibitors of Nerve Growth Factor Mediated Neurite Outgrowth
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An asymmetric synthesis of C14-desmethylene corialactone D is described on the basis of strategic application of a metallacycle-mediated annulative cross-coupling reaction, a Still [2,3]-Wittig rearrangement, and Morken's hydroxyl-directed diboration reac
- Leon, Robert M.,Ravi, Divya,An, Jennifer S.,Del Genio, Carmen L.,Rheingold, Arnold L.,Gaur, Arti B.,Micalizio, Glenn C.
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- A Modular, Enantioselective Synthesis of Resolvins D3, E1, and Hybrids
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Resolvins D3 and E1 are important signaling molecules in the resolution of inflammation. Here, we report a convergent and flexible strategy to prepare these natural products using Hiyama-Denmark coupling of five- and six-membered cyclic alkenylsiloxanes to connect three resolvin fragments, and control the stereochemistry of the natural product (Z)-alkenes. The modular nature of this approach enables the synthesis of novel resolvin hybrids, opening up opportunities for more-extensive investigations of resolvin biology.
- Anderson, Edward A.,Elbert, bryony L.,Llaveria, Josep,Streatfeild, penelope E.,Urbitsch, Felix
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supporting information
(2020/02/28)
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- Synthesis of Cyclic Alkenyl Dimethylsiloxanes from Alkynyl Benzyldimethylsilanes and Application in Polyene Synthesis
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Cyclic dimethylalkenylsiloxanes, useful motifs for (Z)-selective Hiyama cross-coupling, are accessed from alkynyl benzyldimethylsilanes featuring adjacent allylic or homoallylic oxygen substituents by semihydrogenation/debenzylation/cyclization. While formation of 5- and 6-membered rings can be achieved from the free alcohols using fluoride or silanolate, allylic acetate precursors to 5-membered rings display distinct modes of activation. The utility of these compounds is demonstrated through the preparation of a variety of (Z)-alkene-containing polyenes and application to a concise total synthesis of leukotriene B3.
- Gudmundsson, Haraldur G.,Kuper, Christian J.,Cornut, Damien,Urbitsch, Felix,Elbert, Bryony L.,Anderson, Edward A.
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- Synthesis of Cyclic Alkenyl Dimethylsiloxanes from Alkynyl Benzyldimethylsilanes and Application in Polyene Synthesis
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Cyclic dimethylalkenylsiloxanes, useful motifs for (Z)-selective Hiyama cross-coupling, are accessed from alkynyl benzyldimethylsilanes featuring adjacent allylic or homoallylic oxygen substituents by semihydrogenation/debenzylation/cyclization. While formation of 5- and 6-membered rings can be achieved from the free alcohols using fluoride or silanolate, allylic acetate precursors to 5-membered rings display distinct modes of activation. The utility of these compounds is demonstrated through the preparation of a variety of (Z)-alkene-containing polyenes and application to a concise total synthesis of leukotriene B3
- Gudmundsson, Haraldur G.,Kuper, Christian J.,Cornut, Damien,Urbitsch, Felix,Elbert, Bryony L.,Anderson, Edward A.
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p. 14868 - 14882
(2019/12/02)
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- Effect of the substituents at the silicon of (ω-chloroalkyl)silanes on the alkylation to benzene
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(ω-Chloroalkyl)silanes [Cl3-mMemSi(CH2)n-Cl: m=0-3, n=1-3] underwent Friedel-Crafts alkylation with benzene in the presence of aluminum chloride to give alkylated products. Such alkylation reactions took place at temperatures ranging from room temperature (m=0-1, n=2, 3; m=3, n=1) to 80 (m=1, 2; n=1) and 200°C (m=0; n=1), depending on the substituent(s) of the silicon and the alkylene-chain spacer between the silicon and C-Cl bond of (ω-chloroalkyl)silanes. In the alkylation to benzene, the reactivities of (ω-chloroalkyl)silanes increase as the number (m) of methyl-group(s) at the silicon and the alkylene length between the silicon and C-Cl bond increases. While decomposition of alkylation products was observed at two more methyl groups substituted at silicon in the cases of (chloromethyl)silanes such as (chloromethyl)dimethylchlorosilane and (chloromethyl)trimethylsilane. The reaction with (chloromethyl)trimethylsilane occurred at room temperature to give trimethylchlorosilane, toluene and xylene via a decomposition reaction of the products. No (trimethylsilylmethyl)benzene was formed. In the alkylation to benzene, the reactivity of (ω-chloroalkyl)silanes decreases in the following order: m=3>2>1>0; n=3>2?1. The results are consistent with the stability of the carbocation generated by the complexation of (ω-chloroalkyl)silanes with aluminum chloride.
- Yoo, Bok Ryul,Hyun Kim, Jeong,Lee, Ho-Jin,Lee, Kang-Bong,Nam Jung, Il
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p. 239 - 245
(2007/10/03)
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- Acid-catalyzed cyclization of vinylsilanes bearing a hydroxy group: A new method for stereoselective synthesis of disubstituted tetrahydrofurans
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In the presence of a catalytic amount of TsOH or TiCl4, (Z)-5-silyl-4-penten-1-ols ((Z)-1) are smoothly cyclized to 2-silylmethyl-substituted tetrahydrofurans. This cyclization is applicable to the construction of a tetrahydropyran ring. The silyl group and the geometry of the C-C double bond strongly influence the cychzation rate. TBDMS and benzyldimethylsilyl groups considerably accelerate the cyclization in comparison with a dimethylphenylsilyl group, and (E)-vinylsilanes show much lower reactivity than the corresponding (Z)-isomers. The cyclization proceeds by stereospecific syn addition of the hydroxy group. Vinylsilanes 17, 19, and 21, (Z)-5-silyl-4-penten-1-ols bearing a substituent on the methylene tether, smoothly undergo the acid-catalyzed cyclization to give trans-2,5-, cis-2,4-, and trans-2,3-disubstituted tetrahydrofurans, respectively, with moderate to high stereoselectivity. The silyl group of some cychzed products can be easily converted into a hydroxy group with stereochemical retention.
- Miura,Okajima,Hondo,Nakagawa,Takahashi,Hosomi
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p. 11348 - 11357
(2007/10/03)
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- Esters of (Hydroxymethyl)diorganylsilanes: Synthesis and Thermally Induced Rearrangement
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Twenty silanes of the type R1R2Si(H)CH3OR3 (A) were synthesized 1,R2 = Me, Ph, 1-naphthyl, PhCH2, Me3SiCH2; OR3 = OC(O)Me, OC(O)CF3, OS(O)CF3, OP(O)Ph2, OC(O)Cl> and studied for their thermal behaviour.The silanes A undergo a thermally induced rearrangement to give the corresponding silanes R1R2Si(OR3)Me (B).For compounds with OR3 = OC(O)Cl, an additional decarboxylation takes place to yield the chlorosilanes R1R2Si(Cl)Me.Except for the derivatives with OR3 = OC(O)Cl, the energetic (reaction enthalpy) and kinetic data (reaction order, frequency factor, enthalpy and entropy of activation) of these reactions were studied by means of differential scanning calorimetry (DSC).In addition the kinetics of all reactions were investigated by 1H-NMR spectroscopy.The transition state of the rearrangement was investigated by an ab initio study based on the model compound H3SiCH2OC(O)H MeH2SiOC(O)H>.The theoretical data and the experimentally obtained energetic and kinetic data are discussed in terms of mechanistic aspects of the rearrangement reaction A -> B.
- Tacke, Reinhold,Wiesenberger, Frank,Becker, Beate,Rohr-Aehle, Regine,Schneider, Petra B.,et al.
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p. 591 - 606
(2007/10/02)
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- Palladium-Catalyzed Germylation of Organic Halides with a Digermane. Unexpected Formation of Germylene-Insertion Type Products
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Organic halides (RX) underwent dehalogenative germylation and germylene insertion type reactions with ClMe2GeGeMe2Cl in the presence of Pd(PPh3)4 as catalyst to give RGeMe2Cl and RGeMe2X respectively.
- Reddy, Prabhakar N.,Hayashi, Teruyuki,Tanaka, Masato
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p. 677 - 680
(2007/10/02)
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- 1H-CIDNP During the Reaction of Heavy Carbene Analogues R2M (M = Si, Ge, Sn; R = Me, n-Bu) with Halides
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During the reaction of photochemically generated silylenes Me2Si: with PhCH2Cl, PhCH2Br, and Ph2CHCl, 1H-CIDNP is observed in the products of insertion reactions into the C-X bonds (X = Cl, Br) and in the abstraction products Ms2SiX2 indicating the occurrence of a radical abstraction-recombination reaction.The silylenes react from singlet states.Me2Si: reacts with CH2=CHCH2Cl without CIDNP phenomena in a concerted way. (n-Bu2Sn)6 reacts with EtBr via a radical chain mechanism without the appearance of free stannylenes n-Bu2Sn: as intermediates.
- Lehnig, Manfred,Klaukien, Heino,Reininghaus, F.
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p. 1411 - 1414
(2007/10/02)
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- Zur Synthese von Siloxanen XIV. Die Umsetzung von Chlorsilanen mit Silanolen im sauren Medium
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The reactions of aryldimethylchlorosilanes with benzyldimethylsilanol in C6D6/dioxane (2.8/1) have been investigated by 1H NMR spectroscopy.Fast substituent exchange reactions were observed in the presence of H2O or HCl.In this process both substances establish chlorosilane/silanol equilibria which are related to the concetration of H2O and HCl formed.A ρ-value of 1.3 was found for the reaction of substituted aryldimethylchlorosilanes with benzyldimethylsilanol in the presence of H2O.In time the equilibria are disturbed by condensation processes.
- Ruehlmann, K.,Grosse-Ruyken, H.,Scheller, D.,Scheim, U.
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- Carbanion Rearrangements of ω-Phenyl-ω-(trimethylsilyl)alkyllithium Compounds: Intramolecular Reactions of Benzyltrimethylsilanes with a Carbon-Lithium Bond
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ω-Phenyl-ω-(trimethylsilyl)alkyllithium compounds show four out of five theoretically conceivable possibilities for intramolecular stabilization depending on the solvent and on the chain length n.While transmetalation of a methyl group at the silicon atom by a 1,(n+2) proton transfer is observed in any case, the intramolecular 1,n shift of the benzylic proton does only take place with n >/= 4.The main reaction, however for n = 3 and 4 only, is represented by the 1,n trimethylsilyl shift via a cyclic ate complex as an intermediate which partly splits off methyllithium yielding the corresponding silacycloalkane derivatives.In going from diethyl ether to THF as the solvent, the silyl shifts are more accelerated than the proton shifts.In no case, however, a Grovenstein-Zimmermann rearrangement involving phenyl migration took place.Degenerate silyl shifts starting from α-deuterated ω-(trimethylsilyl)alkyllithium compounds could not be detected either.Only by introduction of a second trimethylsilyl group into the 3 position a 1,3-(C -> C)-trimethylsilyl shift is initiated again.
- Maercker, Adalbert,Stoetzel, Reinhard
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p. 1695 - 1706
(2007/10/02)
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- REACTIONS IN THE CHLOROSILANE-SILANOL-SILOXANE SYSTEM
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We obtained the first ?*-values and ES-values for siloxy groups by spectroscopic and kinetic methods.Detailed mechanistic investigations are performed on the hydrolysis of chlorosilanes, the cleavage of Si-O-Si bonds by HCl, and the substituent exchange reaction between silanols and chlorosilanes.
- Ruehlmann, K.
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p. 139 - 152
(2007/10/02)
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- CONVERSION OF DISILANES TO FUNCTIONAL MONOSILANES. XII. THE PALLADIUM(0)-CATALYZED DECHLORINATIVE SILYLATION OF BENZYLIC CHLORIDES WITH METHYLCHLORODISILANES. A FACILE ROUTE TO BENZYLMETHYLCHLOROSILANES
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This paper describes the facile dechlorinative silylation of benzylic chlorides of types XC6H4CH2Cl (X = H, Me and Cl) and ClCH2C6H4CH2Cl (o-, m- and p-isomers) with methylchlorodisilanes ClMe2SiSiMe2Cl, ClMe2SiSiMeCl2 and Cl2MeSiSiMeCl2 in the presence of Pd(PPh3)4 to give the corresponding benzylmethylchlorosilanes in good to high yields.
- Matsumoto, Hideyuki,Kasahara, Miyuki,Matsubara, Ikuya,Takahashi, Masatoshi,Arai, Takeshi,et al.
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- A CONVENIENT SYNTHESIS OF BENZYLMETHYLCHLOROSILANES BY THE PALLADIUM-CATALYZED DECHLORINATIVE SILYLATION OF BENZYLIC CHLORIDES WITH METHYLCHLORODISILANES
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Benzylmethylchlorosilanes were prepared in high yields by the dechlorinative silylation of benzylic chlorides with methylchlorodisilanes MenSi2CI6-n (n = 2, 3, and 4) in the presence of a catalytic amount of Pd(PPh3)4.
- Matsumoto, Hideyuki,Kasahara, Miyuki,Matsubara, Ikuya,Takahashi, Masatoshi,Nakano, Taichi,Nagai, Yoichiro
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p. 399 - 400
(2007/10/02)
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- Sila Perfumes, I. Sila Analogues of Tertiary Carbinols as Perfumes
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Silanols RR'R''SiOH 7 which are analog to carbinols 1 with strong odour in the region of flowery notes (lily of the valley-hyacinth-rose) were prepared via reaction steps (3) and partially unknown intermediates 6.Sila perfumes 7 are similar in intensity and spectrum of odour to 1 but a shift from lily of the valley towards hyacinth notes is generally observed.
- Wrobel, Dieter,Tacke, Reinhold,Wannagat, Ulrich,Harder, Ulrich
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p. 1694 - 1704
(2007/10/02)
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