We developed a chromium-catalyzed, photochemical, and linear-selective alkylation of aldehydes with alkylzirconium species generated in situ from a wide range of alkenes and Schwartz’s reagent. Photochemical homolysis of the C–Zr bond afforded alkyl radicals, which were then trapped by a chromium complex catalyst to generate the alkylchromium(III) species for polar addition to aldehydes. The reaction
Halogen-magnesium exchange of various aryl halides is achieved with a magnesium ate complex at low temperatures; Tributylmagnesate ((Bu3MgLi)-Bu-n) induces facile iodine-magnesium exchange at -78 degreesC. Dibutylisopropylmagnesate ((PrBu2MgLi)-Pr-i-Bu-n) is more reactive than (Bu3MgLi)-Bu-n, and this reagent accomplishes selective bromine-magnesium exchange at -78 degreesC. This procedure is utilized for the preparation of various polyfunctionalized arylmagnesium species. The exchange of alkenyl halides using this method proceeds with retention of configuration of the double bond.
Preparation of Highly Functionalized Grignard Reagents by an Iodine-Magnesium Exchange Reaction and its Application in Solid-Phase Synthesis
At -40°C aryl iodides that contain other functional groups can be selectively converted into Grignard reagents, which react with electrophiles such as benzaldehyde in the usual manner [Eq. (a)]. Aryl bromides and iodides that are immobilized as esters on a Wang resin behave analogously.
The Barbier−Grignard-Type Carbonyl Alkylation Using Unactivated Alkyl Halides in Water
作者:Charlene C. K. Keh、Chunmei Wei、Chao-Jun Li
DOI:10.1021/ja029649p
日期:2003.4.1
The aqueousBarbier-Grignard-typealkylation of aldehydes with unactivatedalkyl iodides and bromides was developed. By using a combination of zinc and cuprous iodide, catalyzed by indium(I) chloride, we successfully added tertiary, secondary, and primary alkylhalides to various aromatic aldehydes in 0.07 M aqueous Na2C2O4. A mechanistic rationale for the success of the reaction has been proposed
开发了醛与未活化的烷基碘和溴化物的水性 Barbier-Grignard 型烷基化反应。通过使用由氯化铟 (I) 催化的锌和碘化亚铜的组合,我们成功地将叔、仲和伯烷基卤化物添加到 0.07 M Na2C2O4 水溶液中的各种芳香醛中。已经提出了反应成功的机械原理。