Preparation from Halogen Compounds and Metal

Direct Preparation from Halogen Compounds and Metal 

In some cases, the preparation of solutions of alkenyllithium or Grignard compounds is synthetically attractive. Vinyl bromide, for example, can be converted in THF with magnesium into vinylmagnesium bromide with excellent results [74]. This Grignard solution can be used for the preparation of a number of derivatives, e.g. H2C=CH—SiMe3 and (H2C=CH)4Sn. Other aliphatic alkenyl-magnesium bromides may be obtained in a similar way. 

Solutions of cycloalkenyllithium can be obtained with excellent results from the readily available chlorocycloalkenes and chipped lithium at temperatures between 20 and 35 °C. Elimination of HC1 does not occur at all. Pieces of broken glass are added to scratch the salt from the metal surface ([9], compare also Ref. [76])  

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