Synthesis of Highly Substituted Racemic and Enantioenriched Allenylsilanes via Copper-Catalyzed Hydrosilylation of (<i>Z</i>)-2-Alken-4-ynoates with Silylboronate
Copper-catalyzed highly efficient hydrosilylation reaction of enynoates was developed. Under simple reaction conditions, various di-, tri-, and tetrasubstituted racemic allene products could be obtained in high yields. The asymmetric 1,6-addition of silyl group to the (Z)-2-alken-4-ynoates could be achieved under mild reaction conditions to afford the silyl-substituted enantioenriched chiral allene
A Pd(II)-catalyzed mild and highly regioselective 6-endo cyclization/allylation reaction of enynoates with simple allylic alcohols has been developed. Under mild reaction conditions, the vinyl palladium species generated in situ after cyclization could insert C–C double bond of allylic alcohol through cross-coupling reaction and lead to the formation of allyl pyrone via β-OH elimination. This cascade
Palladium-Catalyzed Difunctionalization of Internal Alkynes via Highly Regioselective 6-<i>Endo</i> Cyclization and Alkenylation of Enynoates: Synthesis of Multisubstituted Pyrones
An efficient Pd(II)-catalyzed difunctionalization reaction of internal alkynes is reported. In this reaction, various enynoates and electron-deficient alkenes were used for the syntheses of useful highly substituted pyrone derivatives via a 6-endo cyclization and subsequent alkenylation pathway. The corresponding products could be obtained in moderate to good yields under very mild reaction conditions
Unexpected Multiple Electrophilic Addition Reaction of (<i>Z</i>)-Alk-2-en-4-ynoates with <i>N</i>,<i>N</i>-Dibromo-<i>p</i>-toluenesulfonamide (TsNBr<sub>2</sub>): A Highly Diastereoselective Synthesis of Densely Functionalized Aziridines
作者:Ruwei Shen、Xian Huang
DOI:10.1021/ol902446h
日期:2009.12.17
;A novel electrophilic addition reaction of (Z)-alk-2-en-4-ynoates and TsNBr2 is reported, providing a facile and highly stereoselective synthesis of densely functionalized aziridine derivatives.
Regiodivergent Hydrosilylation of Polar Enynes to Synthesize Site‐Specific Silyl‐Substituted Dienes
Herein, we present catalyst‐regulated switchable site‐selective hydrosilylation of enynes, which are suitable for a wide range of alkyl and aryl substituted polar enynes and exhibit excellent functional group compatibility. Under the optimized conditions, silyl groups can be precisely installed at various positions of 1,3‐dienes. While α‐ and γ‐silylation products were obtained under platinum‐catalytic systems, β‐silylation products were delivered with [Cp*RuCl]4 as catalyst. This process lead to the formation of 1,3‐dienoates with diverse substitutions, which would pose challenges with other methodologies.