2916-68-9Relevant academic research and scientific papers
Synthesis of silylated alkylboronic acids and esters via hydroboration of allylic and vinylic trimethylsilanes
Cytarska,Kaczanowska,Zaidlewicz
, p. 1587 - 1594 (2008/09/18)
Representative allylic trimethylsilanes and isopropenyltrimethylsilane were hydroborated with dichloroborane, and the products were transformed into the corresponding ssor γ-trimethylsilylboronates. Synthesis of 2-trimethylsilylethylboronic acid and its diethyl ester via hydroboration of trimethylvinylsilane with diisopinocampheylborane, followed by liberation of α-pinene is described.
Synthesis of COX-2 and FAAH inhibitors
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, (2008/06/13)
Methods for preparing indoles that are useful COX-2 inhibitors and intermediates useful in such methods are described.
Tetrafluoroazidoaniline and method of making and using the same
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, (2008/06/13)
The invention is directed to a novel compounds comprising 4-azidotetrafluoroaniline and the alkyl, acyl and sulfonamide derivatives thereof and to methods of making and using the same. The novel compounds are useful as a photoaffinity probe to study protein structure and function. Two methods for preparing 4-azidotetrafluoroaniline are disclosed, each employing a stable carbamate intermediate from which the 4-azidotetrafluoroaniline is derived.
Synthesis of germatranyl derivatives of esters of carboxylic acids via organometallic (Si, Ge, Sn) reagents
Zaitseva, Galina S.,Livantsova, Ljudmila I.,Nasim, Mohammed,Karlov, Sergei S.,Churakov, Andrci V.,Howard, Judith A. K.,Avtomonov, Evgeni V.,Lorbcrth, Joerg
, p. 739 - 746 (2007/10/03)
Trialkylstannyl esters of tris(2-hydroxyalkyl)amines, N(CH2CHROSnAlk3)3 (9-11) (R = H, Me; Alk = Et, Bu), react with X3GeC(R1)H(R2)COOR3 (12-17) (X = Cl or Br; R1, R2 = H, Me, Ph, SiMe3, COOEt; R3 = Me, Et) to give esters of α-germatranylcarboxylic acids, N(CH2CHRO)3GeQ(R1)MR2)-COOR 3 (1-8), in high yields. The synthesis of esters 12-17 is reported. Esters of α-germatranyldiphenylacetic acid 24 and 25 can be obtained by treatment of diphenylketene with Et3SnOMe to give in situ Et3SnC(Ph2)COOMe (23), followed by reaction with GeCL, to give in situ Cl3GeC(Ph2)COOMe (22) and further reactions with 9 or 11, respectively. Reduction of germatrane 6 with LiAlH4 in diethyl ether leads to cleavage of the germanium-carbon bond with subsequent formation of (2-hydroxyethyl)trimethylsilane. The crystal structures of 3, 6, and 7 are reported. 1-Acyloxygermatranes 26 and 27 are obtained by treatment of 1-methoxygermatrane (28) with diphenyl- and dichloroacetic acid, respectively. VCH Verlagsgesellschaft mbH,.
THE ASYMMETRIC HYDROBORATION OF SIMPLE ALKENYLSILANES: CHIRAL α-SILYLALKYL-BORANES AND ALCOHOLS
Soderquist, John A.,Lee, Shwn-Ji Hwang
, p. 4033 - 4042 (2007/10/02)
The detailed study of the asymmetric hydroboration of various vinylsilanes with monoisopinocampheylborane (IPCBH2) is presented.In all cases, β substitution on the vinylsilane gives monomeric dialkylborane adducts with the boryl group α to the silicon.These studies shown that the larger the groups on silicon are, the more positive the influence on the enatioselectivity of the process.Moderate asymmetric induction (24-40percent) is observed only for vinyl silanes wich contain a substituent trans to the silicon.A model for the asymmetric hydroboration of alkenes with this reagent is proposed.The complete charactarization of the borane intermediates was achieved employing NMR (11B, 13C, 1H, 29Si).
Effects of Volume and Surface Property in Hydrolysis by Acetylcholinesterase. The Trimethyl Site
Cohen, Saul G.,Elkind, Jerome L.,Chishti, S. Bano,Giner, Jose-L. P.,Reese, Heide,Cohen, Jonathan B.
, p. 1643 - 1647 (2007/10/02)
β-Substituted ethyl acetates, XCH2CH2OCOCH3, have been prepared, and their hydrolysis by acetylcholinesterase has been studied.Log of enzymic reactivity, normalized for intrinsic reactivity in hydrolysis by hydroxide, log(kcat/Km)n, rises linearly with increasing refraction volume, MR (or RD25), for substrates with β-X = H, Cl, Br, CH3CH2, (CH3)2CH, (CH3)2S+, (CH3)3N+, and (CH3)3C.Larger substituents may by accommodated, (CH3)3Si and (CH3CH2)3N+, with no further increase in rate.Substrates with β-substituents CH3S, CH3S(O), (CH3)3N+(OH), and CH3S(O2) are less reactive than consistent with the relation with MR by factors of 5-40, indicating that hydrophobic surface and desolvation of the substrate-enzyme interface may be necessary for maximum reactivity correlated with MR.Values of log (kcat/Km)n for substrates with β-substituents X = CH3S, Cl, Br, CH3CH2, (CH3)2CH, (CH3)3C, and (CH3)3Si rise linearly with increasing hydrophobicity, ?, but reactivity of substrates with X = (CH3)3N+ and (CH3)2S+ are more reactive than consistent with a relation to ? by factors of 300 and 40 and with X = CH3S(O2), CH3S(O), and (CH3)2N+(OH), by factors of 7-100.Reactivity appears related to (i) volume of the β-substituent and its fit in its subsite, which is trimethyl rather than anionic, and (ii) the hydrophobicity of its surface.
A CONVENIENT SYNTHESIS OF β-(TRIMETHYLSILYL)ETHANOL
Mancini, Michael L.,Honek, John F.
, p. 3249 - 3250 (2007/10/02)
A novel, simple and high yield synthesis of β-(trimethylsilyl)ethanol in pure form is reported.
DEOXYMETALATION REACTIONS. THE MECHANISMS OF DEOXYSILYLATION OF MONO-TRIMETHYLSILYL-AND BIS-TRIMETHYLSILYL-SUBSTITUTED ALCOHOLS AND A COMPARISON TO THE MECHANISM OF DEOXYSTANNYLATION AND DEOXYPLUMBYLATION
Davis, Dennis D.,Jacocks, Henry M.
, p. 33 - 47 (2007/10/02)
The relative rates of acid-catalyzed deoxysilylation of 2-trimethylsilyl-1-hydroxyethane, 4, 1-trimethylsilyl-2-hydroxypropane, 5, 1,3-bis(trimethylsilyl)-2-hydroxypropane, 6, and 1-trimethylsilyl-2-methyl-2-hydroxypropane, 7, were found to be 1 : 103.30 : 105.92 : 106.77, respectively, in 9 vol percent aqueous-methanol at 40 deg C.These rates are directly proportional to the sum of the ?+ constants of the substituents on the carbon bearing the nucleofuge (ρ+ = -11).The additive rate-accelerating effect of two trimethylsilyl groups requires equal conjugativen bystabilization by each trimethylsilyl group, and a mechanism involving a hyperconjugatively-stabilized carbocation intermediate is proposed.In contrast, the deoxymetalation reactions of the triphenyltin-, triphenyllead-, and iodomercury-analogs exhibit very different structure-reactivity relationships and have been described as proceeding through concerted E2-like or bridged-ion mechanisms.These mechanistic regimes are reconciled by considering the conjugative interactions, electrofugalities and nucleophilic solvent assistance at the organometal-leaving groups in terms of Thornton's Reacting Bond Rules.This analysis suggests a spectrum of merging mechanisms, the acid-catalyzed deoxysilylation representing one extreme, the E1M (carbocation intermediate) mechanism and the other Group IV deoxymetalation reactions more nearly concerted E2M-paths.
