Boranes exchange reactions

Borane exchange reactions— Also borazanes by transamination s. 17, 690... 

Without additional reagents Borane exchange reactions Phosphine boranes from borazanes... 

BCl, BBr, and BI undergo exchange reactions to yield mixed boron hahdes. Exchange reactions also occur with trialkyl, triaryl, trialkoxy, or triaryloxy boranes and with diborane. Anhydrous metal bromides and iodides can be prepared by the exchange reaction of the metal chloride or oxide and BBr or BI (21)-... 

Tris(diphenylmethyleneamino)borane was obtained according to Eq. (30). Exchange reactions of monomeric and dimeric iminochloroboranes with various fluorides could not be effected. However, this lack of reaction is to be expected, since it is well known from borazine chemistry that substitutions which would require a structural change in order to obtain a stable product will not occur 20>. (Diphenylketimino)trimethylsilane (rather than diphenylketimine lithium) has been utilized successfully to prepare (diphenylmethyleneamino) dihaloboranes. This type of reaction is in accordance with earlier observa-... 

Boron trichloride undergoes several exchange reactions with dihorane, other boron halides and trialkyl-, triaryl-, or triaryloxy boranes (Lower, L.D. 1978. Boron compounds (halides). In Kirk-Othmer Encyclopedia of Chemical Technology, 3rd. ed. pp 129-135. New York Wiley Interscience). The reactions occur at ambient or lower temperatures ... 

The mechanisms of these exchange reactions as well as of the related exchanges with boron halides, tris(dialkylamino)boranes, and boron alkyls has been interpreted to proceed through a four-center transition state (255, 258, 260). 

Besides the iodine-zinc exchange reaction, the boron-zinc exchange reaction proves to be an excellent method for preparing a broad range of polyfunctional diorganozincs (Scheme 5.8). The exchange reaction for primary diethylalkyl boranes proceeds at room temperature and is complete within a few minutes. 

An example for the use of the boron-zinc exchange reaction for copper-mediated SN2 -substitutions of allylic electrophiles is the hydroboration of nitroolefin 130 with diethylborane, followed by successive transmetallation of the borane 131 with diethylzinc and CuCN-2LiCl, and final trapping with allyl bromide to give the product 133 with 83% yield over four steps (Scheme 34).34,34a This transformation again demonstrates the tolerance of the method towards functional groups and acidic hydrogen atoms. 

H-D Exchange Reaction of Borane-Lewis Base Adducts by Rhenium Polyhydride Complexes... 

Alkyl and aryl exchange reactions between trialkyl alanes and trialkyl or triaryl boranes have been very fully investigated (188). The exchange of ligands, which occurs very rapidly even at room temperature, occurs through the association products like ... 

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