| 1. |
- Kaiser, N. F. K., et al.
(författare)
-
Microwave-mediated palladium-catalyzed asymmetric allylic alkylation; an example of highly selective fast chemistry
- 2000
-
Ingår i: Journal of Organometallic Chemistry. - Royal Inst Technol, Dept Chem Organ Chem, SE-10044 Stockholm, Sweden. Univ Uppsala, Uppsala Biomed Ctr, Dept Organ Pharmaceut Chem, SE-75123 Uppsala, Sweden.. - 0022-328X .- 1872-8561. ; 603:1, s. 2-5
-
Tidskriftsartikel (refereegranskat)abstract
- Highly enantioselective palladium-catalyzed microwave-mediated fast chemistry has been performed on dimethyl malonate alkylation of(rac)-1,3-diphenylallyl-1-acetate (1). Utilizing the recently developed palladium-phosphineoxazoline catalytic system, with general stability at elevated temperatures (less than or equal to 145 degrees C), quantitative yields of greater than or equal to 97% and ee values of up to >99% were obtained after very short irradiation times (15-300 s, TOF up to 7000 h(-1)).
|
|
| 2. |
- Bahadorikhalili, Saeed, et al.
(författare)
-
N-sulfonyl ketenimine as a versatile intermediate for the synthesis of heteroatom containing compounds
- 2021
-
Ingår i: Journal of Organometallic Chemistry. - : Elsevier. - 0022-328X .- 1872-8561. ; 939
-
Forskningsöversikt (refereegranskat)abstract
- The introduction of more facile and atom efficient methods for the synthesis of organic linear and cyclic compounds is the aim of various researchers worldwide. N-sulfonyl ketenimine is an interesting intermediate in modern organic synthesis. N-sulfonyl ketenimine is capable of selective production of various heteroatom containing compounds, based on the functional groups in the structure of this intermediate. Several linear and cyclic compounds are synthesized from this intermediate. In this review, the role of N-sulfonyl ketenimine is studied as an intermediate in several organic syntheses.
|
|
| 3. |
- Belda, Oscar, et al.
(författare)
-
Chiral bispyridylamide metal complexes as catalysts for the enantioselective adddition of TMSCN to aldehydes
- 2004
-
Ingår i: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X .- 1872-8561. ; 689:23, s. 3750-3755
-
Tidskriftsartikel (refereegranskat)abstract
- The use of (1R,2R)-N,N'-bis(2-pyridinecarboxyamido)-1,2-diphenylethane metal complexes as catalysts for the enantioselective addition of trimethylsilyl cyanide to aldehydes is described. Enantioselectivities up to 70% ee were obtained with a Ti(IV) catalyst. Complexes with Zr(IV), Sc(III), Yb(III) and Cu(II) afforded less selective catalysts. For the Zr(IV) complex, a rate and selectivity enhancement was observed when adding 0.5 equiv. of water with respect to the catalyst. Studies of the metal complexes involved in the reaction were carried out by means of H-1 NMR spectroscopy. A Zr complex was shown by X-ray crystallography to exhibit distorted octahedral coordination, with the four nitrogen atoms of the doubly deprotonated ligand essentially in one plane.
|
|
| 4. |
- Cadu, Alban, et al.
(författare)
-
Development of iridium-catalyzed asymmetric hydrogenation : New catalysts, new substrate scope
- 2012
-
Ingår i: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X .- 1872-8561. ; 714, s. 3-11
-
Forskningsöversikt (refereegranskat)abstract
- A review. The asym. hydrogenation of olefins is a tremendously powerful tool used to synthesize chiral mols. The field was pioneered using rhodium- and ruthenium- based catalysts; however, catalysts based on both of these metals suffer from limitations, such as the need for directing substituents near or even adjacent to the olefin. Iridium-based catalysts do not suffer from this flaw and can thus hydrogenate a wide variety of olefins, including some tetra substituted ones. It is also possible for iridium-based catalysts to hydrogenate hetero-π bonds such as those found in heteroarom. rings. This review summarizes the contributions made to this field by the authors in the past few years. [on SciFinder(R)]
|
|
| 5. |
- Gao, Weiming, et al.
(författare)
-
Facile and highly efficient light-induced PR3/CO ligand exchange : A novel approach to the synthesis of (mu-(SCH2NPrCH2S)-Pr-n)Fe-2(CO)(4)(PR3)(2)
- 2007
-
Ingår i: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X .- 1872-8561. ; 692:7, s. 1579-1583
-
Tidskriftsartikel (refereegranskat)abstract
- A straightforward and efficient transformation of the Fe-S complex [(mu-SCH2NPrCH2S)Fe-2(CO)(6)] to its double phosphine coordinated analogues [(mu-(SCH2NPrCH2S)-Pr-n)Fe-2(CO)(4)(PR3)(2)] (R = Ph, Me) is described. The single crystal structure of the PPh3-disubstituted Complex [(mu-(SCH2NPrCH2S)-Pr-n)Fe-2(CO)(4)(Ph3P)(2)] (3) showed that both of the phosphine ligands take an apical/apical instead of a basal/ basal or an apical/basal configuration.
|
|
| 6. |
- Gerdin, Martin, 1976-, et al.
(författare)
-
Enantioselective silicon-boron additions to cyclic 1,3-dienes catalyzed by the platinum group metal complexes
- 2008
-
Ingår i: Journal of Organometallic Chemistry. - : Elsevier B. V.. - 0022-328X .- 1872-8561. ; 693:23, s. 3519-3526
-
Tidskriftsartikel (refereegranskat)abstract
- Silaborations of 1,3-cyclohexadiene and 1,3-cycloheptadiene were achieved using catalysts prepared from different combinations of phosphorus ligands and group 10 metal compounds. For the six-membered compound, 1,4-adducts with up to 82% ee were obtained employing Pt(0) and phosphoramidite ligands. For the seven-membered diene optimal conditions were found using catalysts based on Ni(0), but the highest selectivity observed was merely 22% ee. No improvement of the chiral induction was obtained using chiral silylboranes in combination with chiral phosphoramidite ligands in the additions to 1,3-cyclohexadiene. The adduct obtained from cyclohexadiene was used in allylborations of aldehydes under microwave irradiation to produce homoallylic alcohols with moderate to good diastereoselectivity.
|
|
| 7. |
|
|
| 8. |
- Hülsen, M., et al.
(författare)
-
Theoretical investigation of thermally and photochemically induced haptotropic rearrangements of chromium ligands on naphthalene systems
- 2011
-
Ingår i: Journal of Organometallic Chemistry. - : Elsevier. - 0022-328X .- 1872-8561. ; 696:24, s. 3861-3866
-
Tidskriftsartikel (refereegranskat)abstract
- The description of chemical reactions by means of quantum mechanical methods is an important task and gets even more challenging if excited states have to be considered. This work focuses on the haptotropic rearrangements of chromium atoms bearing three coligands which migrate on a naphthalene-like system. The reactions are either thermally or photochemically controllable and thus the systems are candidates for molecular switches. We propose a detailed reaction scheme for the investigated system. Furthermore, we provide a detailed analysis of the important steps of the reaction cycle. In comparison to previous publications, the scope of this work also involves the quantum mechanical treatment of excited states in order to describe occurring photon absorption processes in a proper way. Linear response time-dependent density functional theory calculations were carried out to describe the molecules' responses to the external electromagnetic perturbations.
|
|
| 9. |
- Jimenez-Halla, J. Oscar C., et al.
(författare)
-
Organomagnesium clusters : Structure, stability, and bonding in archetypal models
- 2011
-
Ingår i: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X .- 1872-8561. ; 696:25, s. 4104-4111
-
Tidskriftsartikel (refereegranskat)abstract
- We have studied the molecular structure and the nature of the chemical bond in the monomers and tetramers of the Grignard reagent CH(3)MgCl as well as MgX(2) (X = H, Cl, and CH(3)) at the BP86/TZ2P level of theory. For the tetramers, we discuss the stability of three possible molecular structures of C(2h), D(2h), and T(d) symmetry. The most stable structure for (MgCl(2))(4) is D(2h), the one for (MgH(2))(4) is C(2h), and that of (CH(3)MgCl)(4) is T(d). The latter is 38 kcal/mol more stable with chlorines in bridge positions and methyl groups coordinated to a Mg vertex than vice versa. We find through a quantitative energy decomposition analysis (EDA) that the tetramerization energy is predominantly composed of electrostatic attraction Delta V(elstat) (60% of all bonding terms Delta V(elstat) + Delta E(oi)) although the orbital interaction Delta E(oi) also provides an important contribution (40%).
|
|
| 10. |
- Johansson, A, et al.
(författare)
-
Chiral diethylzinc complexes with diamine ligands : synthesis, crystal structure and enantioselective solvent-free alkylation
- 2005
-
Ingår i: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X .- 1872-8561. ; 690:16, s. 3846-3853
-
Tidskriftsartikel (refereegranskat)abstract
- In search for conglomerates of stereochemically labile organometallic reagents, three new complexes between diethylzinc and diamine ligands have been synthesized and structurally characterized by single-crystal X-ray diffraction methods. Ligands include N,N,N',N'-tetraethylethylenediamine (teeda), N-isopropyl-N,N',N'-trimethylethylenediamine (itmeda), and (-)-sparteine (spa). Diethylzinc forms monomeric complexes, exhibiting a distorted tetrahedral coordination geometry around zinc in all three complexes, viz. [ZnEt(2)(teeda)] (1), [ZnEt(2)(itmeda)] (2), and [ZnEt(2)(spa)] (3). Both 1 and 2 are stereochemically labile and exhibit chiral complexes, displaying different types of conformational chirality, but they form racemic crystals. By using the chiral crystals of 3 in a nucleophilic addition to benzaldehyde in the absence of solvent at low temperature, an increase in ee from approximately 8 to 10% was obtained (compared to the same reaction in solution). It thus seems feasible, not only to retain the enantioselectivity obtained in solution, but perhaps even to increase the ee by using solventless reactions.
|
|
