82111-98-6Relevant articles and documents
Chemistry of boron. 130. The reaction of organolithium compounds with borane donors. Preparation and isolation of lithium monoorganotrihydroborates
Biffar, Werner,N?th, Heinrich,Sedlak, Dieter
, p. 579 - 585 (2008/10/08)
The reactions of a series of organolithium compounds with the borane donors BH3·THF, BH3·SMe2, and BH3·NMe3 have been studied in order to develop a general synthesis of lithium organotrihydroborates, LiRBH3. Starting from RLi and BH3 in THF, all members of the series LiR4-nBHn, are formed irrespective of reaction conditions. Bulky substituents R prevent the formation of LiBR4, with BR3 being produced instead. Much higher proportions of LiRBH3 result from the interaction of RLi and BH3·SMe2, with low temperature favoring their formation. Crystalline LiMe2CHBH3 and LiMe3CBH3 can be obtained by this method in good yield. However, LiBH4 is an inevitable byproduct. Other compounds are also formed in minor quantities. Temperatures of >80°C are required for the reaction of RLi with BH3·NMe3, and LiPhBH3·TMEDA and LiPhCH2BH3·TMEDA were isolated in 35 and 90% yield, respectively. Increasing the bulkiness of R (e.g., CMe3) favors deprotonation of BH3·NMe3 over amine displacement. Either LiMe2NCH2BH3 or [Me2NCH2BH2]2 is formed depending on the reaction conditions.
