Mild and Phosphine-Free Iron-Catalyzed Cross-Coupling of Nonactivated Secondary Alkyl Halides with Alkynyl Grignard Reagents
作者:Chi Wai Cheung、Peng Ren、Xile Hu
DOI:10.1021/ol501087m
日期:2014.5.2
cross-coupling of nonactivated secondary alkylbromides and iodides with alkynyl Grignardreagents at room temperature has been developed. A wide range of secondary alkyl halides and terminal alkynes are tolerated to afford the substituted alkynes in good yields. A slight modification of the reaction protocol also allows for cross-coupling with a variety of primary alkyl halides.
REGIOSELECTIVE 1,5-ENYNE SYNTHESIS FROM ORGANOBORANES
作者:Shoji Hara、Yoshitaka Satoh、Akira Suzuki
DOI:10.1246/cl.1982.1289
日期:1982.8.5
2-Alkynylboranes prepared from 2-propynyl chloride and trialkylboranes react readily with allylic halides in the presence of cuprous iodide to give 1,5-enynes regioselectively.
Allyl cyanides are found to add across alkynes in the presence of a nickel/P(4-CF3-C6H4)(3) catalyst to give polysubstituted 2,5-hexadienenitriles with defined stereo- and regiochemistry. Use of AlMe2Cl or AlMe3 as a Lewis acid cocatalyst accelerates the reaction and expands the substrate scope significantly. The cyano group in the allylcyanation products can be transformed to a hydroxymethyl or aminomethyl group to afford highly substituted allylic alcohols or amines. alpha-Siloxyallyl cyanides also add across alkynes selectively at the less hindered gamma-carbon to allow introduction of 3-oxo-propyl functionality after hydrolysis of the resulting silyl enol ethers. This particular carbocyanation reaction has been applied to the stereoselective construction of the trisubstituted double bond of plaunotol, an antibacterial natural product active against Helicobacter pylori.
HARA, SHOJI;SATOH, YOSHITAKA;SUZUKI, AKIRA, CHEM. LETT., 1982, N 8, 1289-1290