Coupling of boranes

Coumarones s. Benzofurans Coupling of boranes 16, 753 Coupling, oxidative... 

The field of borane chemistry continues to expand as evidenced by the extent of published literature in the field during the past years borane lectures [1] included transition metal-promoted coupling of boranes and carboranes [2], the kinetics and mechanisms of the thermolysis and photolysis of binary boranes [3], organoboranes for synthesis [4], and a description of a career in organoborane chemistry [5]. 

Recently, we have developed an alternative synthesis that enables the formation of bulky and electron-rich Af-phosphinomethyl-substituted NHC metal complexes in just three steps (Scheme 10.9) [51]. Further, this procedure does not rely on the isolation of air-sensitive trialkylphosphines. The coupling of borane-protected di-tert-butylphosphine and the chloromethylated imidazohum salts R-40 (R = tBu, Mes) with w-butyl lithium generated the air-stable protected imidazolium salts R-41. In case of an Af-mesityl substitution, this compound could be converted into the palladium allyl complex Mes-42 in a high-yielding one-pot procedure. This feature could encourage the development of new trialkylphosphine-NHC hybrid ligands. 

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