24423-97-0Relevant academic research and scientific papers
Palladium-catalyzed hiyama cross-couplings of aryl arenesulfonates with arylsilanes
Zhang, Liang,Wu, Jie
supporting information; experimental part, p. 12250 - 12251 (2009/02/05)
Palladium-catalyzed efficient Hiyama cross-coupling reaction of aryl arenesulfonate with arylsilane is described. The desired carbon-carbon bond formation proceeds under mild conditions with good functional group tolerance. Copyright
REDUCTIVE COUPLING OF BENZOIC ACID HALIDES AND ESTERS USING LOW-VALENT TITANIUM
Dang, Y.,Geise, H. J.
, p. 375 - 380 (2007/10/02)
The reductive coupling of (substituted) benzoic acid chlorides and esters is achieved using low-valent titanium, generated from TiCl3 and LiAlH4.Both acid chlorides and esters seem to follow the same two reaction pathways: one path via tolanes to stilbenes, the other via benzils to complex mixtures of products arising from reduction and further coupling reactions.Although the exact product balance depends upon the reaction conditions the major product is (substituted) cis-stilbene.
Conformations and Rotational Barriers of 1,3-Diphenylallyllithium Compounds
Boche, Gernot,Buckl, Klaus,Martens, Diether,Schneider, Dieter R.
, p. 1135 - 1171 (2007/10/02)
The phenyl substituents of the 1,3-diphenylallyl anions 10 (gegenion lithium, solvent tetrahydrofuran) can exist in the exo,exo-, endo,exo- and/or endo,endo-conformations.We have investigated the influence of substituents R at C2 on the equilibria of these solvent separated ion pairs.While 10a (R = H) is the only one to exist predominantly in the exo,exo-conformation, and in 10b and c (R = CH3 and CN, respectively) the endo,exo-conformers predominate, in 10d, e and f (R = C2H5, C6H5 and iPr, respectively) there is increasing preference for the endo,endo-conformation, which in 10g (R = tBu) is the dominant (>/= 95percent) conformation.A vast congestion in the endo,endo-conformation is avoided by a rotation of the phenyl rings out of the plane of the allyl carbon atoms, and an expansion of the sp2 angles in the allyl moiety.The rotational barriers around the allyl anion bonds decrease from 19.1 kcal*mol-1 (10a) to 12.5 kcal*mol-1 (10f).Since this trend parallels to the above mentioned shift of the equilibria, it is due to ground state effects.The rotational barriers are only slightly (10a,b) if at all influenced by gegenion effects, which is in sharp contrast to the parent allyl "anion".Therefore, the rotational barriers of the allyl anions 10 are qualified for a comparison with the corresponding radicals and cations.Furthermore, with ΔG(excit)273 deg C = 19.1 kcal*mol-1 as a lower limit value for the rotational barrier of the parent allyl anion, one can estimate that the true value of this species must be close to barriers calculated with STO-3G and 4-3l-G programs (ca. 26 kcal*mol-1).
