Enantioselective Synthesis of All-Carbon Quaternary Stereogenic Centers via Copper-Catalyzed Asymmetric Allylic Alkylation of (<i>Z</i>)-Allyl Bromides with Organolithium Reagents
作者:Martín Fañanás-Mastral、Romina Vitale、Manuel Pérez、Ben L. Feringa
DOI:10.1002/chem.201406006
日期:2015.3.9
A copper/phosphoramidite catalyzed asymmetric allylic alkylation of Z trisubstituted allyl bromides with organolithium reagents is reported. The reaction affords all‐carbon quaternary stereogenic centers in high yields and very good regio‐ and enantioselectivity. This systematic study illustrates the crucial role of the olefin geometry of the allyl substrate on the outcome of the reaction and provides
alkynes with arylzinc iodide•lithium chloride complexes in acetonitrile. The scope of the arylzincation is wide enough to use unfunctionalized alkynes, such as 6-dodecyne, as well as arylacetylenes. The inherent functional group compatibility of arylzinc reagents allows preparation of various functionalized styrene derivatives. The reaction is applicable to the efficient and stereoselective synthesis
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.
Grignard allylic substitution reaction catalyzed by 1,2,3-triazol-5-ylidene magnesium complexes
Allylic chlorides and phosphates reacted with alkyl-Grignard reagent in an S(N)2'-selective manner in the presence of a catalytic amount of 1,2,3-triazol-5-ylidenes to provide a-branched alkenes. (C) 2013 Elsevier Ltd. All rights reserved.
Fujiwara,Y. et al., Israel Journal of Chemistry, 1976, vol. 15, p. 262 - 264