7450-04-6Relevant academic research and scientific papers
para-Selective Benzylation of Aryl Iodides by the in situ Preparation of ArIF2: a Hypervalent Iodine-Guided Electrophilic Substitution
Chaudhry, Azka,Hyatt, I. F. Dempsey,Im, Haram,Jones, Taro J.,Noorollah, Jennifer,Siddiqi, Fatima,Singh, Nirvanie,Spatola, Nicholas R.
supporting information, (2020/04/16)
Hypervalent iodine-guided electrophilic substitution (HIGES) was described previously for the para-selective benzylation of aryl-λ3-iodane diacetates. One drawback of the method was the synthesis and isolation of hypervalent iodine starting mat
NHC complexes of cobalt(II) relevant to catalytic C-C coupling reactions
Przyojski, Jacob A.,Arman, Hadi D.,Tonzetich, Zachary J.
, p. 723 - 732 (2013/03/28)
Alkyl compounds of cobalt(II) containing aryl-substituted N-heterocyclic carbene ligands have been prepared by reaction of the precursor chloro complexes [CoCl2(IMes)2] and [Co2Cl2(μ-Cl) 2(IPr)2] (IMes = 1,3-dimesityl-imidazol-2-ylidene; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) with Grignard reagents. Examples of alkyl complexes possessing both four-coordinate and three-coordinate geometries are reported. The chloro complex [CoCl2(IMes) 2] adopts a pseudotetrahedral geometry displaying an S = 3/2 ground state, whereas the alkyl complex [Co(CH 3)2(IMes)2] adopts a square-planar geometry consistent with an S = 1/2 ground state. In contrast to [Co(CH3)2(IMes)2], [Co(CH2SiMe 3)2(IPr)] exhibits a three-coordinate trigonal-planar geometry displaying an S = 3/2 ground state. The catalytic efficacy of [CoCl2(IMes)2] in Kumada couplings is examined, as is the chemistry of the alkyl complexes toward CO. The structure and reactivity of these compounds is discussed in the context of C-C coupling reactions catalyzed by cobalt NHCs.
Atom-efficient metal-catalyzed cross-coupling reaction of indium organometallics with organic electrophiles
Perez,Sestelo,Sarandeses
, p. 4155 - 4160 (2007/10/03)
The novel metal-catalyzed cross-coupling reaction of indium organometallics with organic electrophiles is described. Triorganoindium compounds (R3In) containing alkyl, vinyl, aryl, and alkynyl groups are efficiently prepared from the correspond
Nucleophile-assisted cleavage of benzyltrialkylsilane cation radicals
Dockery, Kevin P.,Dinnocenzo, Joseph P.,Farid, Samir,Goodman, Joshua L.,Gould, Ian R.,Todd, William P.
, p. 1876 - 1883 (2007/10/03)
The cation radicals of benzyltrialkylsilanes have been generated using photoinduced electron transfer and characterized using transient absorption spectroscopy. Absolute rate constants for nucleophile-assisted C-Si bond cleavage have been determined, for different nucleophiles in different solvents and with different substituents on the phenyl ring. The short lifetime (-9 s) of the parent benzyltrimethylsilane cation radical in acetonitrile was unambiguously shown to be due to a rapid nucleophile-assisted bond cleavage, with the solvent acting as the nucleophile. Even in less polar solvents, such as dichloromethane, the lifetime of benzyltrimethylsilane cation radical is quite short (ca. 20 ns) unless trace amounts of water, which acts as an efficient nucleophile, are removed. Consistent with the nucleophile-assisted cleavage mechanism for the benzyltrialkylsilanes, sterically-demanding substituents on silicon decrease the rate constant for cleavage by as much as 4 orders of magnitude, depending upon the nucleophile. Similarly, increasing steric crowding on the nucleophile also decreases the rate constant, although smaller changes in the rate constants are observed. Electron-donating substituents (4-methyl and 4-methoxy) on the phenyl group also lead to a substantial decrease in the rate constant for cleavage of the cation radicals. When measurements are performed in the least nucleophilic solvent and under conditions that minimize contributions from adventitious nucleophiles, the lifetimes of the cation radicals of the benzyltrialkylsilanes can be so long that the rate of pseudofirst-order decay can not be accurately determined. If the cation radicals undergo unimolecular C-Si bond cleavage (i.e., not nucleophile-assisted) under these conditions, the rate constant for this process is estimated to be less than 104 s-1.
Thermally induced rearrangement of α-zirconocenyl thioethers: Carbon-carbon bond formation via a transition-metal hydroxymethyl or metalloxirane analogue
Ward, A. Steven,Mintz, Eric A.,Kramer, Michael P.
, p. 8 - 12 (2008/10/08)
The thermal rearrangement of α-zirconocenyl thioethers (η5-C5H5)2Zr(Ar)[CH(SC 6H5)(Si(CH3)3)] (Ar = C6H5, p-C6H4CH3, p-C6H4OCH3, p-C6H4Cl) and (η5-C5H5)2ZrC6H 5[CH(SCH3)(Si(CH3)3)] in toluene solution follows clean first-order kinetics to produce (η5-C5H5)2Zr(SC 6H5)[CH(Ar)(Si(CH3)3)] and (η5-C5H5)2Zr-(SCH 3)[CH(C6H5)(Si(CH3)3)]. Labeling studies using (η5-C5H5)2Zr(p-C 6H4CH3)[CH(SC6H 5)(Si(CH3)3)] and (η5-C5H5)2ZrC6H 5[CD(SC6H5)(Si(CH3)3)] show this rearrangement to be intramolecular. Activation parameters for the rearrangement of (η5-C5H5)2ZrC6H 5[CH(SC6H5)(Si(CH3)3)] were found to be ΔH? = 20.30 (43) kcal/mol and ΔS? = -19.0 (2) eu. It is proposed that this rearrangement proceeds by intramolecular nucleophilic attack (migration) of the aryl group to the methylene carbon with commensurate breaking of the C-S bond. A Hammett plot of log (kobsd) for the rearrangement of (η5-C5H5)2Zr(Ar)[CH-(SC 6H5)(Si(CH3)3)] versus σp produces a straight line (p = -2.22 (9)), supporting this mechanism.
Reaction of trimethylsilanes with Arenes and Alk-1-enes in the Presence of Lewis Acid: Syntheses of - and (1-Arylthioalk-3-enyl)-trimethylsilanes
Ishibashi, Hiroyuki,Nakatani, Hiroshi,Umei, Yoshizumi,Yamamoto, Wako,Ikeda, Masazumi
, p. 589 - 594 (2007/10/02)
Treatment of equimolar amounts of the trimethylsilanes (2) or (3) and electron-rich arenes with an equimolar amount of Lewis acid (SnCl4 or TiCl4) gave the Friedel-Crafts reaction products, trimethylsilanes (4) or (5), in high yields.Similar treatment of the chlorides (2) or (3) with alk-1-enes gave ene type products, trimethylsilanes (12) or (13), in moderate yields.Some chemical transformations of these products are also described.
AN ELECTROREDUCTIVE SYNTHESIS OF ALLYLSILANES AND BENZYLSILANES
Shono, Tatsuya,Matsumura, Yoshihiro,Katoh, Susumu,Kise, Naoki
, p. 463 - 466 (2007/10/02)
The electrochemical reduction of benzyl and allyl halides carried out in the presence of chlorotrimethylsilane afforded the corresponding benzylsilanes and allylsilanes in satisfactory yields.
INTRODUCTION OF AN ARYLTHIO(TRIMETHYLSILYL)METHYL GROUP INTO ARENES BY FRIEDEL-CRAFTS REACTION: SYNTHESIS OF ARYLMETHYLTRIMETHYLSILANES
Ishibashi, Hiroyuki,Nakatani, Hiroshi,Umei, Yoshizumi,Ikeda, Masazumi
, p. 4373 - 4374 (2007/10/02)
Friedel-Crafts reactions of trimethylsilanes (1a, b) with arenes gave trimethylsilanes (2a,b), which were converted into arylmethyltrimethylsilanes (3) by reduction with Raney nickel.
α-Lithium Alkyls of α-Trimethylsilyl-p-xylenes and the Synthesis of p-C6H4(CH2SnMe3)2 from a New Di-Grignard Reagent: Crystal Stucture of 2>
Leung, Wing-Por,Raston, Colin L.,Skelton, Brian W.,White, Allan H.
, p. 1801 - 1808 (2007/10/02)
Metallation of the p-xylene compounds p-C6H4(CHRR')(CHR''R''') (R,R',R'',R'''=H or SiMe3) with n(tmen)> (tmen=NNN'N'-tetramethylethylenediamine) or n(pmdien)> (pmdien=NNN'N''N''-pentamethyldiethylenetriamine) occurs selectively at the benzylic carbon atom(s) (Cα) in a manner dependent on the degree of substitution and the tertiary amine.Four of the organolithium complexes generated have been isolated as crystalline solids and the molecular structure of one, 2>, has been determined from single-crystal X-ray diffraction data.The p-xylenediyl moiety is planar with the trimethylsilyl groups trans to each other, being related by an inversion centre.There is evidence of a dominant p-quinodimethanide bonding contribution, with each lithium, on opposite sides of the C8H6Si2 plane, interacting unsymmetrically with both Cα and its adjacent ring-carbon atom α 2.10(1) and Li-Cβ 2.38(1) Angstroem>.A high-yield synthesis of a di-Grignard reagent derived from 1,4-bis(chloromethyl)benzene in thf (tetrahydrofuran) which yields a compound of composition n after ca. 1 h is described.The utility of this compound is illustrated by the synthesis of p-C6H4(CH2SnMe3)2 from SnMe3Cl.
