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411.
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414.
Jing Li Adriano Bauer Giovanni DiMauro Nuno Maulide 《Angewandte Chemie (International ed. in English)》2019,58(29):9816-9819
A synthetically useful approach for the direct α‐arylation of carbonyl compounds through a novel oxidative C?C bond activation is reported. This mechanistically unusual process relies on a 1,2‐aryl shift and results in all‐carbon quaternary centers. The transformation displays broad functional‐group tolerance and can in principle also be applied as an asymmetric variant. 相似文献
415.
Boni A Marchetti F Pampaloni G Zacchini S 《Dalton transactions (Cambridge, England : 2003)》2010,39(45):10866-10875
The novel cationic diiron μ-allenyl complexes [Fe(2)Cp(2)(CO)(2)(μ-CO){μ-η(1):η(2)(α,β)-C(α)(H)=C(β)=C(γ)(R)(2)}](+) (R = Me, 4a; R = Ph, 4b) have been obtained in good yields by a two-step reaction starting from [Fe(2)Cp(2)(CO)(4)]. The solid state structures of [4a][CF(3)SO(3)] and of the diruthenium analogues [Ru(2)Cp(2)(CO)(2)(μ-CO){μ-η(1):η(2)(α,β)-C(α)(H)=C(β)=C(γ)(R)(2)}][BPh(4)] (R = Me, [2a][BPh(4)]; R = Ph, [2c][BPh(4)]) have been ascertained by X-ray diffraction studies. The reactions of 2c and 4a with Br?nsted bases result in formation of the μ-allenylidene compound [Ru(2)Cp(2)(CO)(2)(μ-CO){μ-η(1):η(1)-C(α)=C(β)=C(γ)(Ph)(2)}] (5) and of the dimetallacyclopentenone [Fe(2)Cp(2)(CO)(μ-CO){μ-η(1):η(3)-C(α)(H)=C(β)(C(γ)(Me)CH(2))C(=O)}] (6), respectively. The nitrile adducts [Ru(2)Cp(2)(CO)(NCMe)(μ-CO){μ-η(1):η(2)-C(α)(H)=C(β)=C(γ)(R)(2)}](+) (R = Me, 7a; R = Ph, 7b), prepared by treatment of 2a,c with MeCN/Me(3)NO, react with N(2)CHCO(2)Et/NEt(3) at room temperature, affording the butenolide-substituted carbene complexes [Ru(2)Cp(2)(CO)(μ-CO){μ-η(1):η(3)-C(α)(H)[upper bond 1 start]C(β)C(γ)(R)(2)OC(=O)C[upper bond 1 end](H)] (R = Me, 10a; R = Ph, 10b). The intermediate cationic compound [Ru(2)Cp(2)(CO)(μ-CO){μ-η(1):η(3)-C(α)(H)[upper bond 1 start]C(β)C(γ)(Me)(2)OC(OEt)C[upper bond 1 end](H)](+) (9) has been detected in the course of the reaction leading to 10a. The addition of N(2)CHCO(2)Et/NHEt(2) to 7a gives the 2-furaniminium-carbene [Ru(2)Cp(2)(CO)(μ-CO){μ-η(1):η(3)-C(α)(H)[upper bond 1 start]C(β)C(γ)(Me)(2)OC(OEt)C[upper bond 1 end](H)](+) (11). The X-ray structures of 10a, 10b and [11][BF(4)] have been determined. The reactions of 4a,b with MeCN/Me(3)NO result in prevalent decomposition to mononuclear iron species. 相似文献
416.
Adriano Pinto Mariano Caliane Bastos Borba Costa Dejanira de Franceschi de Angelis Francisco Maugeri Filho Daniel Ibraim Pires Atala Maria Regina Wolf Maciel Rubens Maciel Filho 《Applied biochemistry and biotechnology》2009,159(2):366-381
In this work, the mathematical optimization of a continuous flash fermentation process for the production of biobutanol was
studied. The process consists of three interconnected units, as follows: fermentor, cell-retention system (tangential microfiltration),
and vacuum flash vessel (responsible for the continuous recovery of butanol from the broth). The objective of the optimization
was to maximize butanol productivity for a desired substrate conversion. Two strategies were compared for the optimization
of the process. In one of them, the process was represented by a deterministic model with kinetic parameters determined experimentally
and, in the other, by a statistical model obtained using the factorial design technique combined with simulation. For both
strategies, the problem was written as a nonlinear programming problem and was solved with the sequential quadratic programming
technique. The results showed that despite the very similar solutions obtained with both strategies, the problems found with
the strategy using the deterministic model, such as lack of convergence and high computational time, make the use of the optimization
strategy with the statistical model, which showed to be robust and fast, more suitable for the flash fermentation process,
being recommended for real-time applications coupling optimization and control. 相似文献
417.
We express the multiplicities of the irreducible summands of certain tensor products of irreducible integrable modules for an affine Kac-Moody algebra over a simply laced Lie algebra as sums of multiplicities in appropriate excellent filtrations (Demazure flags). As an application, we obtain expressions for the outer multiplicities of tensor products of two fundamental modules for \(\widehat {\mathfrak {sl}}_{2}\) in terms of partitions with bounded parts, which subsequently lead to certain partition identities. 相似文献
418.
419.
Palimécio G. Guerrero Paulo R. de Oliveira Adriano C.M. Baroni Francisco A. Marques Ricardo Labes Miguel J. Dabdoub 《Tetrahedron letters》2012,53(13):1582-1586
A novel one-pot synthesis of 1,1-dihalo-1-alkenes and 1,1-bis(butyltelluro)-1-alkenes was developed from hydrozirconation of alkynylzinc bromide with Cp2Zr(H)Cl and subsequent capture of the Zn/Zr 1,1-heterodimetallo-1-alkene intermediates with halogen and tellurium electrophiles. These protocols, which include multiple reactions in a one-pot procedure, allow the preparation of the potentially useful haloketene acetals and telluroketene acetals from terminal alkynes, under mild conditions and in a good yield. 相似文献
420.
We study a special type of almost complex structures, called pure and full and introduced by T.J. Li and W. Zhang (, 2007), in relation to symplectic structures and Hard Lefschetz condition. We provide sufficient conditions to the existence of
the above type of almost complex structures on compact quotients of Lie groups by discrete subgroups. We obtain families of
pure and full almost complex structures on compact nilmanifolds and solvmanifolds. Some of these families are parametrized
by real 2-forms which are anti-invariant with respect to the almost complex structures. 相似文献