Aryl-containing amines, enantiomeric

In all the entries but the first two, the phosphorus atoms contain two aryl groups. Some crowded diphosphine boranes have also been reported (entries 2, 6, 10, 14 and 16-21). In general, good yields for the coupling reaction are observed, even in the latter cases. The diphosphine boranes are obtained as enantiomerically pure white solids or oils, which can be easily deboronated by amines. The diphosphinite borane of entry 1 also deserves some comment because another product could have been formed (Scheme 4.40). 

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