Rhodium(III)-Catalyzed [4+1] Annulation of Aromatic and Vinylic Carboxylic Acids with Allenes: An Efficient Method Towards Vinyl-Substituted Phthalides and 2-Furanones
A highly regio‐ and stereoselective synthesis of 3,3‐disubstituted phthalides from aryl carboxylic acids and allenes using a rhodium(III) catalyst has been demonstrated. The reaction features broad functional group tolerance and provides a simple and straightforward route to the synthesis of various 3‐vinyl‐substituted phthalides. Furthermore, the catalytic reaction can also be applied to the synthesis
The introduction of electronegative substituents onto the silyl group of triaryl(2-silylethylidene)phosphorane promotes eliminative silyl migration relative to the Wittig reaction; the combination of this effect with modification of the phosphorane substituents leads to highly diastereoselective reagents for alkenylation.
Direct Substitution of the Hydroxy Group in Alcohols with Silyl Nucleophiles Catalyzed by Indium Trichloride
作者:Makoto Yasuda、Takahiro Saito、Masako Ueba、Akio Baba
DOI:10.1002/anie.200353121
日期:2004.3.5
Direct Coupling Reaction between Alcohols and Silyl Compounds: Enhancement of Lewis Acidity of Me<sub>3</sub>SiBr Using InCl<sub>3</sub>
作者:Takahiro Saito、Yoshihiro Nishimoto、Makoto Yasuda、Akio Baba
DOI:10.1021/jo061512k
日期:2006.10.1
The combination of InCl3 and Me3SiBr provided an enhanced Lewis acid system that can be used to promote a wide range of direct coupling reactions between alcohols and silyl nucleophiles in non-halogenated solvents, such as hexane or MeCN. The enhanced Lewis acidity of this system was measured by the C-13 NMR in terms of the coordination to an alcohol. Moreover, the interaction between Me3SiBr and the In(III) species was revealed by Si-29 NMR spectral analysis. Highly chemoselective allylations toward a hydroxyl moiety over ketone and acetoxy ones have been demonstrated.
Copper-Catalyzed Regiodivergent and Enantioselective Hydrosilylation of Allenes
branched allylsilanes were formed by judicious choice of solvents. Furthermore, branched allylsilanes were obtained with high enantioselectivity (up to 97% enantiomericexcess) with the aid of a C2-symmetric bisphosphine ligand in the unprecedented asymmetric allene hydrosilylation.