18027-67-3Relevant academic research and scientific papers
Main Group Conjugated Organic Anion Chemistry. 3. Application of Magnesium-Anthracene Compounds in the Synthesis of Grignard Reagents
Harvey, Stephen,Junk, Peter C.,Raston, Colin L.,Salem, Geoffrey
, p. 3134 - 3140 (2007/10/02)
Reaction of magnesium-arene compounds, , 1, and some silylanthracene, and/or tertiary amine analogues, with benzylic and allylic chlorides or bromides, and (Me3Si)3CCl, afford Grignard reagents, RMgX, in modest to high yield for chlorides and negligible to high yield for the bromides, in THF, toluene, and hexane at -10 to 20 deg C.Novel benzylic-type Grignard reagents prepared in high yield include those of 9-(chloromethyl)anthracene, 2-(chloromethyl)pyridine and 8-(chloro(or bromo)methyl)quinoline, and poly-Grignard reagents derived from 1,8-bis(chloromethyl)naphthalene, 2,2'-bis(chloromethyl)-1,1'-binaphthyl, and 1,3,5,-tris(chloro(or bromo)methyl)benzene.Grignard reagent formation occurs via electron-transfer reactions.Aryl and alkyl halides yield mainly products derived from addition of the halide across the 9,10-positions of the anthracenes, via nucleophilic substitution or collapse of a diradical cage 2+, (anthracene)-anion radical, RX-anion radical.>
Carbanion Rearrangements of ω-Phenyl-ω-(trimethylsilyl)alkyllithium Compounds: Intramolecular Reactions of Benzyltrimethylsilanes with a Carbon-Lithium Bond
Maercker, Adalbert,Stoetzel, Reinhard
, p. 1695 - 1706 (2007/10/02)
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.
Asymmetric Synthesis Catalyzed by Chiral Ferrocenylphosphine-Transition-Metal Complexes. 3. Preparation of Optically Active Allylsilanes by Palladium-Catalyzed Asymmetric Grignard Cross-Coupling
Hayashi, Tamio,Konishi, Mitsuo,Okamoto, Yasuo,Kabeta, Keiji,Kumada, Makoto
, p. 3772 - 3781 (2007/10/02)
Asymmetric cross-coupling of the - or -Grignard reagent with alkenyl bromides in the presence of a chiral ferrocenylphosphine-palladium complex, dichloroethylamine>palladium(II) (PdCl2), as a catalyst, gave optically active allylsilanes which contain an asymmetric carbon atom directly bonded to the silicon atom, e.g., (R)-3-phenyl-3-(trimethylsilyl)propene (3a) (95percent ee), (R,E)-1-phenyl-1-(trimethylsilyl)-2-butene (3b) (85percent ee), (R,Z)-3b (24percent ee), (R,E)-1,3-diphenyl-3- (trimethylsilyl)propene (3c) (95percent ee), (S,E)-1-phenyl-3-(trimethylsilyl)-1-butene (14c) (71percent ee), (S,Z)-14c (59percent ee), (S,E)-1-phenyl-3-(triethylsilyl)-1-butene (16c) (93percent ee), (S,E)-3-(triethylsilyl)-2-pentene (16b) (85percent ee), (S,E,E)-2-(dimethylphenylsilyl)-3,5-heptadiene (15d) (45percent ee), and 1-cyclopentene (21) (37percent ee).The configuration and enantiomeric purity of the allylsilanes were determined with the aid of stereoselective oxidative cleavage of the carbon-silicon bond in optically active alkylsilanes.
Carbanion Rearrangements by Intramolecular 1,ω Proton Shifts, III. The Reaction of 2-, 3-, 4-, and 5-Phenylalkyllithium Compounds
Maercker, Adalbert,Passlack, Michael
, p. 540 - 577 (2007/10/02)
Upon addition of THF to a solution of 4-phenylbutyllithium (2) in diethyl ether a rapid intramolecular 1,4 proton shift takes place with the formation of 1-phenylbutyllithium (5).Similarly, although somewhat more slowly, 5-phenylpentyllithium (82) rearranges to 1-phenylpentyllithium (83) via 1,5 proton transfer.The corresponding rearrangements by 1,2 or 1,3 hydrogen shifts, however, starting with 2-phenylethyllithium (1) and 3-phenylpropyllithium (54), respectively, were not detected.With 3-phenylpropyllithium (54) a slow intramolecular 1,5 transfer an ortho proton is observed instead, yielding o-propylphenyllithium (100).The corresponding 1,6 shift with 4-phenylbutyllithium (2) was also detected in a minor amount in addition to the 1,4 proton shift already mentioned.There is no indication, however, for a 1,4 transfer of an ortho proton in 2-phenylethyllithium (1).The reaction products in this case can be exclusively explained by intermolecular transmetallation reactions.All ω-phenylalkyllithium compounds under investigation show interesting side and secondary reactions being rather different in deuterated solvents and in deuteriumfree solvents, respectively, due to the isotope effects.The analysis of the products is accomplished by 1H-NMR spectroscopy and, after derivatization, with the help of a GC-MS-combination.Stereoelectronic reasons are made responsible for the failure of the intramolecular 1,2 and 1,3 proton shift in these systems.
