- [{(dppe)Pt}2B7H11]: An arachno-bimetallanonaborane based on the uncommon n-B9H15 cluster framework
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The first bimetallanonaborane, [{(dppe)Pt)2B7B11], based on the uncommon n-B9H15 cluster framework, is prepared and characterized as a final product from the reaction of pentaborane (9) with [PtCl2(dppe)].
- Macias, Ramon,Rath, Nigam P.,Barton, Lawrence
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- Iron(II) catalyzed reductive radical cyclization reactions of bromoacetals in the presence of NaBH4: optimization studies and mechanistic insights
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5-Exo-trig radical reductive cyclization reactions of bromoacetals are catalyzed by iron in the presence of the reducing agent NaBH4. Both iron(II) and iron(III) were found to effectively mediate these reactions. As shown by cyclic voltammetry, iron(III) can be reduced to an iron(II) precatalyst before passing through an identical reaction mechanism in which monoelectronic activation of the substrate would occur by an anionic hydridoiron(I) complex. Further studies have established that both the substrate (iodo- vs bromo-derivative) and the precatalytic mixture are decisive in determining the reaction outcome.
- Kyne, Sara H.,Lévêque, Christophe,Zheng, Shiwen,Fensterbank, Louis,Jutand, Anny,Ollivier, Cyril
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supporting information
p. 7727 - 7737
(2016/11/18)
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- Direct use of chiral or achiral organophosphorus boranes as pro-ligands for transition metal catalyzed reactions
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Chiral or achiral organophosphorus borane complexes were used without isolation of the free tricoordinate P(III) ligand; thus, the borane adducts could be used either directly with metal salts to perform the catalysis, or they could be decomplexed by DABCO, or cyclooctadiene, and used in situ to generate the catalytic species. Chiral copper, palladium and rhodium complexes prepared using this method, were tested in asymmetric organometallic catalyzed 1,4-addition to 2-cyclohexenone, allylation of Schiff base and hydrogenation of α-acetamidocinnamic acid derivatives, respectively.
- Darcel, Christophe,Kaloun, El Bachir,Merdès, Rachid,Moulin, Dominique,Riegel, Nadège,Thorimbert, Serge,Genêt, Jean Pierre,Jugé, Sylvain
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p. 333 - 343
(2007/10/03)
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- Mono and diphosphine borane complexes grafted on polypyrrole matrix: Direct use as supported ligands for Rh and Pd catalysis
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A new versatile method for the synthesis of supported mono and diphosphines on polypyrrole matrix is described, based on the protective borane complexation of the phosphorus atom. For the first time, the unknown alkylation of a diphosphine ethano bridge, was obtained with near yield close to 70%, leading to its derivative 8 bearing the polymerizable pyrrole group on a side chain. The different supported mono and diphosphine boranes 12-15 have been applied with success in palladium-catalyzed allylation, cross-coupling reaction and in rhodium-catalyzed hydrogenation. It is of particular interest that supported phosphine boranes can be used without previous decomplexation, forming in situ the catalytically active species from Pd(OAc)2 or RhCl3. Moreover, the recoverable polymer could be used again in rhodium-catalyzed hydrogenation with a very good efficiency after several turn-overs. Nethertheless, we may point out that with palladium catalysis, the addition of Pd(dba)2 was necessary to recover the catalytic activity. These results demonstrate that the phosphine borane complexes are key precursors for the synthesis of functionalized mono and diphosphines, and for their direct use in generating catalysts.
- Riegel, Nadege,Darcel, Christophe,Stephan, Olivier,Juge, Sylvain
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p. 219 - 233
(2007/10/03)
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