Boranes heterocyclic

Borane complexes of P-heterocycles as versatile precursors for the synthesis of chiral phosphine ligands used for asymmetric catalysis 98S1391. 

Applications of oxazaphospholidine-borane complexes, cyclic phosphoramides, compounds with N—P=0 function, and other P-heterocycles in enantio-selective catalysis 99SL377. 

Aminomethylphosphines are convenient objects for a comparison of phosphorus and nitrogen donor ability in complexation reactions. Coordination compounds of heterocyclic aminomethylphosphines with metals are discussed in Section VII. In this section we present reactions of aminomethylphosphines with boranes (BH3). 

Bis(a-aminomethyl)phosphines having a mobile hydrogen atom could be expected to undergo a borylation reaction with borane, hydrogen being evolved. In fact, bis(Af-phenylaminomethyl)-phenylphosphine (199) and its sulfide (200) appeared to interact with borane under mild conditions, yielding a new type of phosphorus-boron-containing heterocycle—2-... 

We have compiled important preparations of heteroaryl halides, boranes and stannanes for each heterocycle. The large body of data regarding palladium-mediated polymerization of heterocycles in material chemistry is not focused here neither is coordination chemistry involving palladium and heterocycles. 

Lithium Salts Based on Heterocyclic Anions. Lithium salts based on organic anions where the formal charge is delocalized throughout substituted heterocyclic moieties were also reported sporadically, which included, for example, lithium 4,5-dicyano-l,2,3-triazolate ° and lithium bis(trifluoro-borane)imidazolide (Lild). ° The former was developed as a salt to be used for polymer electrolytes such as PEO, and no detailed data with respect to electrochemistry were provided, while the latter, which could be viewed as a Lewis acid—base adduct between LiBp4 and a weak organic base, was intended for lithium ion applications (Table 13). 

Tris(dimethylamino)borane similarly fails to 3deld a trivalent boron heterocycle, but gives the spiro-compound (CLXV). A monocyclic system of type (CLXVI) does arise from diethylaminodiphenylborane, and of type (CLXVII) from phenylboronic acid and its analogues 436). 

The reductive cleavage of phosphonio-substituents attached to other heterocyclic frameworks was first demonstrated in the reaction of the 3,5-bis-phosphonio-l,2,4-diazaphospholide 15 with NaBH4 or LiBEt3H to yield the zwitterionic borane-complexes 27. Liberation of the free zwitterion 28 was readily feasible by treatment of the complexes with an excess of NEt3 (Scheme 9) [34]. 

A-Amine oxides can be reduced (deoxygenated) to tertiary amines. Such a reaction is very desirable, especially in aromatic nitrogen-containing heterocycles where conversion to amine oxides makes possible electrophilic substitution of the aromatic rings in different positions than it occurs in the parent heterocyclic compounds. The reduction is very easy and is accomplished by catalytic hydrogenation over palladium [736, 737], by borane [738], by iron in... 

The low yield observed in the isomerization of the 2,4,4-trimethylpent-2-ene (28) is because of the facile cyclization of the borane 30, with evolution of hydrogen, to produce a boron heterocycle 31. Oxidation of the reaction mixture provides... 

These results reveal that under isomerization conditions boranes with five carbon atoms or more undergo intramolecular cyclization to produce the boron heterocycle and hydrogen. The reaction is specially facile when the primary hydrogen is available at the 5 position [3]. 

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... 

Instead, it is the goal of this chapter to highlight some conceptually novel developments in the field of HAT reactions. We will concentrate on complexes of borane with N-heterocyclic carbenes (NHCs), on organometallic hydrogen atom donors in stoichiometric and catalytic reactions, and on the activation of water and alcohols for HAT. 

B-Heterocycles and reactions of boranes with heterocycles 93JOM(457)l, 93JOM(457)25. 

Character of bonding in metallacarboranes 91NJC831. nB NMR spectroscopy of B-heterocycles 92CRV325. Three-dimensional aromaticity in deltaedric boranes and carboranes 93IZV1353. 

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