68469-62-5Relevant articles and documents
Intramolecular radical hydrosilylation - The first radical 5-endo-dig cyclisation
Amrein, Stephan,Studer, Armido
, p. 1592 - 1593 (2007/10/03)
Intramolecular radical hydrosilylations using allyloxy- and propargyloxycyclohexadienylsilanes comprising 5-endo-trig as well as 5-endo-dig processes are presented.
The γ-silicon effect. IV. The solvolysis mechanism of 3-(aryldimethylsilyl)propyl p-toluenesulfonates
Fujiyama,Nakashima,Kim,Fujio,Tsuno
, p. 429 - 438 (2007/10/03)
The solvolysis of 3-(aryldimethylsilyl)propyl p-toluenesulfonates was described based on the effects of substituents, solvents, and deuterium isotope, in comparison with the γ-silyl-assisted solvolysis of 3-(aryldimethylsilyl)-2,2-dimethylpropyl toluenesulfonates. The solvent effect on the simple γ-silyl assisted system showed the nucleophilic assistance of solvent, but failed to correlate linearly with the extended Winstein-Grunwald equation, substantiating that the reaction should not proceed through either the formation of the cation intermediate of the SN2 mechanism. This suggested that the reaction occurs in competition between γ-silyl-assisted (kSi) and solvent-assisted (ks) pathways, and that the competition ratio varies with solvents and with aryl substituents. Product analysis revealed that the former pathway gave only cyclopropane and the latter gave only the substitution products. Using product ratios, the overall rate constant (kt) value could be dissected into the partial rate constants kSi and ks for the two pathways. The effects of aryl substitutes at the γ-silyl atom on kSi pathway were correlated with unexalted σ°(normal substituent constant) parameter, giving the ρ values of -1.0 in 60E and -1.32 in 97Tw, and reflecting the delocalization of incipient carbocationic charge by participation of the Si-Cγ bond. The substituent effects on the ks pathway were negligible, which is in line with the remote reaction center in the concerted SN2 mechanism.
The γ-silicon effect on solvolyses of the 3-(aryldimethylsilyl)propyl system
Fujio, Mizue,Nakashima, Tohru,Fujiyama, Ryoji,Kim, Hyun-Joong,Tsuno, Yuho
, p. 612 - 615 (2007/10/03)
The γ-silicon effects in solvolyses were studied mechanistically on 3-(aryldimethylsilyl)propyl tosylates in various solvents based on the substituent effects. The mechanism can be described as competing reactions of the γ-silyl-assisted (kSi) and the solvent-assisted (ks) pathways. Copyright
Stereocontrol in organic synthesis using silicon-containing compounds. A formal synthesis of (±)-thienamycin
Fleming, Ian,Kilburn, Jeremy D.
, p. 2663 - 2671 (2007/10/03)
The lithium enolate Z-11 derived from methyl 3-dimethyl(phenyl)silylbutanoate reacts with the N-silylimines of cinnamaldehyde 12, of 3-trimethylsilylpropynal 18, and of 3-trimethylsilylpropenal 19 to give β-lactams with a high level of stereoselection in
The Regiochemistry and Stereochemistry of the Hydroboration of Allylsilanes
Fleming, Ian,Lawrence, Nicholas J.
, p. 3309 - 3326 (2007/10/02)
The hydroboration of a wide range of allylsilanes 3 and 5-21 is found to be generally regioselective for attachment of the boron to C-3 and hydrogen to C-2 of the allyl unit, and to be generally stereoselective in the sense 1, with attachment of the boron
REGIOCHEMISTRY IN THE HYDROBORATION OF ALLYLSILANES
Fleming, Ian,Lawrence, Nicholas, J.
, p. 2073 - 2076 (2007/10/02)
The hydroboration of most types of allylsilane is highly selective for the formation of the product having the silicon and boron in a 1,3 relationship when the hydroborating agent is 9-BBN.There is only a low degree of correlation between the difference in the chemical shifts of the trigonal carbon atoms on an alkene and the regioselectivity in hydroboration with either borane:THF or 9-BBN.
Diastereoselective Aldol Reactions of β-Silylenolates: A Formal Synthesis of Thienamicin
Fleming, Ian,Kilburn, Jeremy D.
, p. 1198 - 1199 (2007/10/02)
The lithium enolate (1) of benzyl β-phenyldimethylsilylbutanoate reacts with β-phenyldimethylsilylpropionaldehyde (2) to give, with high diastereoselectivity, the aldol product (3), which is converted into the β-lactam (7), a known precursor of thienamyci
Direct Synthesis of Metallacycloalkanones via the Cyclic Hydroboration of Dialkenyl Derivatives of Silicon, Germanium, and Tin
Soderquist, John A.,Hassner, Alfred
, p. 1801 - 1810 (2007/10/02)
The hydroboration of a number of representative dialkenylsilanes was examined to determine the regiochemistry of the addition process.For compounds containing a vinylsilane moiety, the relative amount of products containing the boron atom in a β position with respect to silicon was invariably greater on using thexylborane as opposed to borane-methyl sulfide complex (BMS).Compounds which contain an allylsilane group undergo hydroboration to give exclusively a terminally placed boron adduct for that portion of the molecule.Diisopropenyl and bis(α-styryl) derivatives of silicon, germanium, and tin were directly converted to the corresponding novel metallacyclohexanones by using Pelter's cyanoborate procedure.In several cases, the DCME reaction could also be used to prepare these metallacyclohexanones.The cyanoborate methodology was used to prepare silacycloheptan-4-one and silacyclooctan-5-one systems in an improved manner.Novel disilacycloalkanones and germacyclooctanone systems were also prepared.All metallacycloalkanones were isolated isomerically pure from the simple sequence.Spectroscopic data for reaction intermediates and products are also reported and discussed.
