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The size of a series of typical substituents has been probed by dynamic NMR measurements of the barriers to aryl-aryl rotation of the corresponding biphenyls. The resulting B values are meaningful because only mono-ortho substituted compounds were investig ...
The question is addressed of whether the triruthenium cluster cation Ru-3(mu(2)-H)(3)(eta(6)C(6)H(6))(eta(6)-C6Me6)(2)(mu(3)-O), 1, is a supramolecular, outer-sphere benzene hydrogenation catalyst or is 1 a precatalyst to well-known Ru(0)(n) catalysis ...
π−π interactions in heteroaromatic systems are ubiquitous in biological systems. In the present study, stabilization energies of stacked and hydrogen-bonded dimers of N-heteroaromatic systems (pyridine, pyrazine, sym-triazine, and sym-tetrazine) have been ...
The importance of catalysis in chemistry has not to be proved anymore. Be it homogeneous or heterogeneous catalysis, the constant progresses observed in that field proves its obvious interest. The asymmetric homogeneous catalysis is a method of choice to s ...
Starting with 1,1,1-trifluoroacetone, 3-(trifluoromethyl)-1-(trimethylsilyloxy)-1,3-butadiene has been prepd. as a mixt. of (Z) and (E) isomers. The diene undergoes [4 + 2] cycloaddn. reactions with a variety of dienophiles affording trifluoromethyl-substi ...
After alpha,alpha'-dimetalation, both 2,2'-diallyloxy-1,1'-binaphthyl and 2,2'-di-2-methylallyloxy-1,1'-binaphthyl undergo the Wittig rearrangement with perfect diastereoselectivity. When racemic 1,1'-binaphthyl-2,2'-diol ("BINOL") is used as the starting ...
At low temperature and in the presence of CF3COOH, SO2 undergoes Diels-Alder additions with (E)-1-acetoxybutadiene (8d) giving a 1:10 mixture of diastereomeric 6-acetoxysultines (9d + 10d). The Van't Hoff plot for equilibria 8d + SO2 reversible arrow 9d + ...
A new tandem reaction leads to bicyclic cyclohexene derivatives with complete control of the relative configuration of the four chiral centers formed. The high diastereoselectivity is the consequence of an endo-selective Diels-Alder reaction followed by an ...
Two 1,3-dialkyne-functionalized imidazolium chlorides, 1,3-dipropynylimidazolium chloride and 1,3-dipentynylimidazolium chloride, have been prepared from the direct reaction between the appropriate chloroalkyne and (trimethylsilyl)imidazole. Replacement of ...
The reactivity of various 2-oxyallyl cations toward 2,2'-methylenedifuran (1b), 2,2'-(hydroxymethyl)difuran (1c), 2,2'-(trimethylsilylmethylene)difuran (1d), and di(2-furyl)methanone (1e) has been explored. Difuryl derivatives 1c, 1d, and le refused to und ...
