carbonyl group, cyano group) in an alkyl halide facilitates its cross-coupling reaction with various diorganozincs in the presence of Ni(acac)(2) (7.5-10 mol % in THF/NMP mixtures). These results were used to develop a new general cross-coupling reaction between functionalized diorganozincs and alkyliodides using m- or p-trifluoromethylstyrene as a reaction promotor and Ni(acac)(2) as a catalyst (7.5-10
PtCl<sub>2</sub>-Catalyzed Tandem Enyne Cyclization/1,2 Ester Migration Reaction Controlled by Substituent Effects of All-Carbon 1,6-Enynyl Esters
作者:Xing Huo、Changgui Zhao、Gaoyuan Zhao、Shouchu Tang、Huilin Li、Xingang Xie、Xuegong She
DOI:10.1002/asia.201300018
日期:2013.5
On the move: A novelPtCl2‐catalyzed tandem 1,6‐enyne cyclization/1,2‐acyloxy migration reaction was developed, which was shown to be controlled by substitution effects. Using this method, a series of substituted enol esters containing the cyclopentenyl motif were prepared in moderate to high yields.
Zirconocene-Induced Cocyclisation/Elimination Reactions of 2-Heterosubstituted 1,6-Dienes and 1,6-Enynes
作者:Richard J. Whitby、David R. Owen
DOI:10.1055/s-2005-870029
日期:——
Zirconocene-mediated cocyclisation of 2-heterosubstituted-1,6-dienes and -enynes gave zirconacycles bearing an endocyclic β-leaving group which eliminated under the reaction conditions to provide exocyclic alkylidene groups. The scope of this cyclisation/elimination has been investigated along with further elaboration of the monosubstituted zirconocene intermediates by insertion of alkenyl carbenoids.
A Ring‐Closing Metathesis Approach to Cyclic α,β‐Dehydroamino Acids
作者:Koen F. W. Hekking、Dennis C. J. Waalboer、Marcel A. H. Moelands、Floris L. van Delft、Floris P. J. T. Rutjes
DOI:10.1002/adsc.200700308
日期:2008.1.4
the synthesis and ring-closingmetathesis (RCM) of α,β-dehydroamino acids is described. This sequence has led to the formation of a range of biologically relevant functionalized nitrogen heterocycles. The incorporation of chiral building blocks in the RCM precursors eventually resulted in the formation of optically active 4-substituted cyclic dehydroamino acids. In addition, olefin isomerization under
The addition of a precisely positioned chiralcenter in the tether of a constrained peptide is reported, yielding two separable peptide diastereomers with significantly different helicity, as supported by circular dichroism (CD) and NMR spectroscopy. Single crystal X‐ray diffraction analysis suggests that the absolute configuration of the in‐tetherchiralcenter in helical form is R, which is in agreement