Lithium diisopropylamide-mediated ortholithiations: lithium chloride catalysis.

نویسندگان

  • Lekha Gupta
  • Alexander C Hoepker
  • Kanwal J Singh
  • David B Collum
چکیده

Ortholithiations of a range of arenes mediated by lithium diisopropylamide (LDA) in THF at -78 degrees C reveal substantial accelerations by as little as 0.5 mol % of LiCl (relative to LDA). Substrate dependencies suggest a specific range of reactivity within which the LiCl catalysis is optimal. Standard protocols with unpurified commercial samples of n-butyllithium to prepare LDA or commercially available LDA show marked batch-dependent rates--up to 100-fold--that could prove significant to the unwary practitioner. Other lithium salts elicit more modest accelerations. The mechanism is not discussed.

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عنوان ژورنال:
  • The Journal of organic chemistry

دوره 74 5  شماره 

صفحات  -

تاریخ انتشار 2009