作者:Radim Hrdina、Christian E. Müller、Raffael C. Wende、Katharina M. Lippert、Mario Benassi、Bernhard Spengler、Peter R. Schreiner
DOI:10.1021/ja110685k
日期:2011.5.25
We present a new class of catalysts based on the combination of N,N'-diaryl(thio)ureas and weak silicon Lewis acids (e.g., SiCl(4)). Such silicon-(thio)urea catalysts effectively catalyze the stereospecific rearrangement of epoxides to quaternary carbaldehydes.
Pd-catalyzed selective tandem arylation–alkylation of 1,1-dihalo-1-alkenes with aryl- and alkylzinc derivatives to produce α-alkyl-substituted styrene derivatives
作者:Ji-cheng Shi、Ei-ichi Negishi
DOI:10.1016/j.jorganchem.2003.09.008
日期:2003.12
Trans-selective monoarylation of 1, 1-dibromo- and 1,1-dichloro-1-alkenes (1) can be achieved in > 80% yields and in > 98-99% stereo selectivity with arylzinc bromides in the presence of a catalytic amount of Cl2Pd(DPEphos) or Cl2Pd(dppb), the former permitting cleaner and higher yielding reactions. Although THF is a generally satisfactory solvent, ether and toluene are superior to THF in some cases. The second substitution of (Z)-alpha-bromostyrenes (3) with alkylzincs in the presence of 2 mol% of Pd('Bu3P)(2) proceeds to give the corresponding 2 in >90% yields and in greater than or equal to98-99% stereoselectivity. Although somewhat less satisfactory, the use of Cl2Pd(DPEphos) permits a one-pot tandem arylation-alkylation. (C) 2003 Elsevier B.V. All rights reserved.
Vinylic organoboranes. 11. A highly stereospecific and regiospecific synthesis of trisubstituted alkenes via organoboranes
作者:Herbert C. Brown、Narayan G. Bhat
DOI:10.1021/jo00261a005
日期:1988.12
BROWN, HERBERT C.;BHAT, NARAYAN G., J. ORG. CHEM., 53,(1988) N6, C. 6009-6013