Borane , di-

Bei der Durchfiihrung von Reduktionen mit Diboran-Losungen ist zu beachten, daB die zur Reduktion notige Menge des Hydrids in der Literatur nicht einheitlich, sondern als Di-boran, Boran oder in Hydrid-Aquivalenten angegeben wird. 

Natrinm-flnoro-tiihydrido-borat reduziert Vinyl-halogenide selektiv zu Olefinen (S. 400). Es wird aus Di-boran und Natriumfluorid hergestellt. 

Auch die endstandigen Carboxy-Gruppen in Peptiden bzw. EiweiBen werden durch Di-boran reduziert1. 

Die Reduktion von Dihydroxy-carbonsauren und Hydroxy-dicarbonsauren mit Di-boran bzw. Lithiumalanat ergibt die entsprechenden Triole2. 

Da bei der Reduktion von Oximen und Oxim-Derivaten mit D i bor an und Aluminium-hydrid reduktive Umlagerungen, besonders im ersteren Fall, praktisch nicht ablaufen, eig-nen sie sich besonders zur Herstellung prim. Amine. Die Reduktion von Oximen mit Di-boran fiihrt selbst in Bis-[2-methoxy-athyl]-ather bei 105-110° nicht immer zur Amin-Stufe7 (s. S. 374). 

Figure 4.25. Structure of the (Al2Sb6)12 ion (isostructural with the A12C16 molecule) identified in the Zintl compound Ba3AlSt>3. Another important compound having this structure, consisting of two-centred tetrahedra with a common edge, is the simple di-borane (B2H6).

Auch Alkyl- und Aryl-Grignard-Verbindungen werden in gleicher Weise addiert328. Mit Di-boran in Tetrahydrofuran wird selektiv die 4,5-C,N-Doppelbindung reduziert52 (s.S. 515). 

The hydroboration amination sequence in diglyme is a general procedure for the conversion of olefins to primary amines without rearrangement and with predictable stereochemistry.5 An alternative procedure, using tetrahydrofuran as solvent and either hydroxylamine-O-sulfonic acid or chloramine, is applicable with terminal olefins and relatively unhindered internal and alicyclic olefins.6 O-Mesitylenesulfonylhydroxylamine also gave desired amines in comparable yield.7 Alternative procedures for the hydroboration of olefins use commercially available solutions of di-borane in tetrahydrofuran8 or dimethylsulfide.9... 

The reaction is called hydroboration and is a versatile synthesis of organoboron compounds. One example is the addition of diborane, B2H6, to ethene. Di-borane behaves as though it is in equilibrium with BH3 (B2H6 <= 2BH3), and addition proceeds in three stages ... 

The C-H coupling of aromatic heterocycles with bis(pinacolato)di-borane(4) was carried out in octane at 80-100 °C in the presence of a half equivalent [IrCl(COD)]2-(4,4 -di-tert-butyl-2,2 -bipyridine) catalyst (3 mol%). The reactions of five-membered substrates such as thiophene, furan, pyrrole, and their benzo-fused derivatives exclusively produced 2-borylated... 

The first dibora[2] ferrocenophane (94) was prepared from l,L-dilithioferrocene and l,2-dichlorobis(dimefhylamino)di-borane. A dynamic process due to motion of the cyclopenfa-dienyl rings between staggered and eclipsed conformations was revealed by low-temperature NMR spectroscopy. A number of l,3-dibora[3]ferrocenophanes with B-E-B bridges (95 E=0, S, Se, Te, NR) were reported. Moreover, Wagner used diborylated ferrocenes for the synthesis of doubly bridged switchable ania-metallocenes (96) and (97), in which the bridges are created and... 

Analysis of the microwave spectra of 10 isotopic species of H2N,B2Hs gave the substitution values of the structural parameters shown in Table 3. Unlike bromodiborane, aminodiborane has a structure significantly different from di-borane itself. 

Aminoboranes undergo an interesting reaction when heated with di-borane a borane group is absorbed and aminodiboranes are formed (35, 36). The structure of 7V,jV-dimethylaminodiborane has been determined by electron diffraction (70) it (I) is related to the structure of diborane and to the probable structure of dimeric iV,iV-dimethylaminoborane (II).3 It is likely that all aminodiboranes have similar structures. The first member of the group, H2NB2H5, may be prepared by passing diborane over its... 

Previously, decaborane(14) was synthesized by pyrolysis of hazardous di-borane(6) in elaborate apparatus which precluded the use of the method for general laboratory work.1 The procedure given here is performed in standard glassware employing relatively safe materials and thus makes decaborane(14) generally available for the first time. 

Solution (a) Hydroboration-oxidation occurs with cis addition to the alkane in an anti-Markovnikov fashion. Di-borane can add onto either face of the alkene. Since the overall hydration process occurs in a cis fashion, hyd-... 

Methyl-3-keto-l-pentanol tetrahydro-2-pyranyl ether added at 0-3° during 0.5 hr. to a tetrahydrofuran soln. of (+)-di(isopinocampheyl)borane prepared from di-borane and (—)-a-pinene, stirred overnight at 6-7°, excess hydride decomposed with water, 3 N NaOH followed by 30%-H2O2 added with cooling, and stirred 1.5 hrs. at ca. 40° -> (+)-4-methyl-l-(3R)-dihydroxypentane l-tetrahydro-2-pyranyl ether. Y 91.4%. - Also prepn. of the (—) isomer with (+)-a-pinene and the (+)-(3R)-3-Di-compound with deuteriodiborane prepared from NaBD4 s. E. Caspi and K. R. Varma, J. Org. Chem. 33, 2181 (1968). 

The enamino-ester [318 R = N(CH2>4] was reduced to (318 R = H) using di-borane then acid similar esters were likewise reduced. The disulphonimide (319) reacts with DMSO and sodium bicarbonate to give cycloheptanone (58 %) and cyclo-heptene (22%). ... 

Caution Poison gases such as arsine, di-borane, methyl bromide, nitric oxide, nitrogen dioxide, phosgene, and phosphine pose serious potential hazards to personnel and therefore require special handling. These products must never be handled except by specially trained personnel who are fully aware of the potential hazards involved and who are equipped with such special personal safety apparatus as is necessary in the handling of these products. 

In the first step, hydroboration, an alkene is treated with diborane (6113)2 or B2H1S. Di-borane acts as if it were the monomeric species called borane, (BH3). The boron reagent is usually prepared in an ether solvent such as diethyl ether or tetrahydrofuran. 

In the series for synthesizing dendritic molecules, they prepared various monomers to achieve a directional divergent cascade synthesis. For instance, as shown in Scheme 5, aminotriol 1 was prepared as follows [Eq. (1)] [7] Michael-type addition of nitromethane to acrylonitrile afforded the trisnitrile 2. which was subsequently transformed to the triacid 5. Alternatively, triacid 3 was obtained via a Michael-type addition of nitromethane to methyl acrylate and subsequent hydrolysis of triester 4. Reduction of the acid moieties with di-borane gave nitrotriol 5. Further reduction with Raney nickel yielded the desired aminotriol 1. 

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