Dehydrocoupling of amine-borane adducts

Jaska CA, Temple K, Lough AJ, Manners I (2003) Transition metal-catalyzed formation of boron-nitrogen bonds catalytic dehydrocoupling of amine-borane adducts to form aminoboranes and borazines. J Am Chem Soc 125 9424—9434... 

Clark TJ, Russell CA, Manners I (2006) Homogeneous, titanocene-catalyzed dehydrocoupling of amine-borane adducts. J Am Chem Soc 128 9582-9583... 

Transition metal-catalyzed approaches to boron-nitrogen compounds are potentially of significant importance. Very interestingly. Manners et ah have reported the catalytic dehydrocoupling of primary or secondary amine-borane adducts... 

Scheme 11.13 Catalytic dehydrocoupling of primary amine-borane adducts.

Scheme 11.14 Catalytic dehydrocoupling of secondary amine-borane adducts.

Recently, Manners and co-workers have found another type of reaction, the inorganic process corresponding to Rh-catalysed dehydrocoupling of borane adducts, which is homogeneous or heterogeneous catalysed depending on the substrate, in particular the nature of the Lewis base, phosphine or amine respectively [15]. 

The formation of individual cycloborazanes can be achieved, in some cases, by transition metal-catalysed dehydrocoupling reactions. By using this strategy, secondary amine-boranes are converted to the four-membered ring (H2BNMe2)2 under mild conditions, whereas primary amine-boranes produce borazines. The cyclic pentamer is obtained as the exclusive product from ammonia-borane adduct H3B NH3 employing an iridium(fll) catalyst [see eqn (2.13) in Section 2.3)]. 

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