Cobalt-Mediated Cross-Coupling Reactions of Primary and Secondary Alkyl Halides with 1-(Trimethylsilyl)ethenyl- and 2-Trimethylsilylethynylmagnesium Reagents
[reaction: see text] This paper describes cobalt-mediated cross-coupling reactions of alkyl halides with 1-(trimethylsilyl)ethenylmagnesium bromide and 2-(trimethylsilyl)ethynylmagnesium bromide, respectively. The cobalt system allows for employing secondary as well as primary alkyl halides as the substrates. The reactions offer facile formations of alkyl-alkenyl and alkyl-alkynyl bonds. The reaction
The hydroboration of (trimethylsilyl)ethyne with dialkylboranes and its application to the syntheses of (E)-1-(trimethylsilyl)alk-1-enes and 2-(trimethylsilyl)alk-1-enes
作者:Masayuki Hoshi、Yuzuru Masuda、Akira Arase
DOI:10.1039/p19900003237
日期:——
The reaction of (trimethylsilyl)ethyne 1 with a stoicheiometric amount of dialkylborane 2 proceeds to the monohydroboration stage, giving a mixture of regioisomers, (E)-[2-(trimethylsilyl)-ethenyl]dialkylborane 3 and [1-(trimethylsilyl)ethenyl]dialkylborane 4. In the hydroboration with bulky dialkylboranes, derived from internal alkenes, the former predominates. Successive treatment of the mixture with methyllithium and benzenesulphenyl chloride exclusively affords highly pure (E)-2-alkyl-1-(trimethylsilyl)ethene 6 whose alkyl group migrates from the boron atom, while in the hydroboration with less bulky dialkylboranes, derived from terminal alkenes, the latter predominates. Successive treatment of the mixture with aq. NaOH and iodine exclusively affords highly pure 2-(trimethylsilyl)alk-1-ene 7 whose alkyl group migrates from the boron atom.
HOSHI, MASAYUKI;MASUDA, YUZURU;ARASE, AKIRA, J. CHEM. SOC. PERKIN TRANS. PT 1,(1990) N2, C. 3237-3241