Polyborane reactions with

BioH14 is a mdo-polyborane, therefore, it is expected that it forms adducts with Lewis bases. This is indeed the case but with concomitant loss of hydrogen as shown in Eq. (51). These adducts of the type BioHi2-2L (L = amines, pyridine, phosphines, nitriles, dialkylsulfides inter alia) proved to be versatile reagents. For instance, when triethylamine is used to replace acetonitrile from the adduct not only does the expected replacement occur but in preference also a proton shift (most likely prior to the base displacement reaction) with cluster closure to the decahydro-doso-decaborate(2—) (Eq. 52) ... 

At the same time, interaction of the neutral base 1 with polyboranes or boron trifluoride does occur even at low temperatures (Scheme 17)179. NMR monitoring showed that while 1 with diborane or BF3 gave salts of similar type, 144 and 145, interaction between 1 and decaborane resulted in proton transfer, and reaction with pentaborane led to the formation of ionic compound X+ B9II 4, whose cationic part (X+) remained unidentified. 

While alkynes, nitriles, and isocyanides have long been known to insert a cage carbon into polyboranes (COMC (1982) 5.4.2.6.1 and 5.4.2.6.2), the use of aldehydes to insert a cage carbon was first reported by Bernd Brellochs in 1997 (Figure 5).86 Good yields of 10-vertex monocarbaboranes were obtained from B10H14 with KOH and many aldehydes and this reaction was thus coined the Brellochs reaction. 87... 

Remarkable diastereoselectivity has been achieved in the synthesis of dinucleoside methylphosphonates from the reactions of dichloro-(methyl)phosphine with suitably protected nucleosides at low temperatures.Various phosphapolyboranes have been obtained from the reactions of dichloro(methyl)phosphine with polyborane... 

Reaction of ethylene (and other olefins) with B Hjq occurs with the elimination of H2 from the polyborane to yield the bismethylene-bridged (CH2)2B4Hg ... 

Diborane is not unique among the boron hydrides in its ability to form a carbonyl. High pressure reaction of either pentaborane-f / or tetra-borane-10 with carbon monoxide forms a substance which behaves like borane-carbonyl in its manner of decomposition. The formula of this polyborane-carbonyl has recently been established as OC B Hg (mp, — 114.5° bp, 59.6°) 41a). It reacts with trimethylamine without release of carbon monoxide. 

B.i.c. Palladium-Catalyzed Hydrosilation ofAlkynes. Relatively little has been reported on the Pd-catalyzed hydrosilation of alkynes. This is in sharp contrast with the corresponding hydrostannation of alkynes discussed later in Sect. C. The reaction of terminal alkynes with HSiEts in the presence of polyborane-containing Pd and Pt complexes yielded the results summarized in Scheme 10, which indicate that Pd and Pt catalysts... 

Transition metals such as It were used to control polyborane formation. Metal-assisted borane condensation is demonstrated by the formation of [ara A) o-2,5- Cp ltH]2B4Hs] 791 by the reaction of two BHs THF moieties with the metal centers of [ Cp IrH 2(/r-H)B2Hs] 792. Mild thermolysis of 791, which contains separated B2H4 fragments, results in H2 elimination and the formation of the [ /i ( i-l,2- Cp"lr 2(/t-H)B4H7] 793. 

---