Search results for "Phosphine"
showing 10 items of 618 documents
Ligands hybrides : synthèse et chimie de coordination
2011
This manuscript deals with the synthesis of hybrids ligands and their coordination ability. The first part is dedicated to Cp-imidazole, Cp-imidazolium and Cp-phosphine ligands. Several synthetic routes have been developed to reach these mixed ligands and their coordination chemistry has been studied with titanium. In a second part, a method developed in our laboratory to synthesize phosphine-olefines was applied to obtain a phosphino-diene bearing three potential coordination sites. We have studied the coordination modes of this hybrid ligand using various transition metals and some of the formed complexes were tested in catalysis. In the third part is described the coordination chemistry …
Efficient Synthesis of β-Halogeno Protected L-Alanines and Their β-Phosphonium Derivatives.
2003
Abstract Ring opening of oxazolines, prepared from l -serinates, with trimethylsilyl halides (TMSX) led to β-halogeno-N-benzoyl-α-amino esters in good to excellent yields. Quaternization of triphenylphosphine by the β-bromo or -iodo amino esters gave the corresponding β-phosphonium salts in overall yields of up to 93% and with e.e. >96%. Hydrolysis of the ester function afforded the phosphonium salt bearing an N-benzoyl-α-amino acid substituent, with partial racemization. However, the reaction of the TMSX with the carboxylic salt, prepared by saponification of the starting oxazoline ester, furnished the corresponding β-halogeno-N-benzoyl-α-amino acids in 70–95% yields. Quaternization of tri…
CCDC 216063: Experimental Crystal Structure Determination
2005
Related Article: I.Rojo, F.Teixidor, C.Vinas, R.Kivekas, R.Sillanpaa|2004|Chem.-Eur.J.|10|5376|doi:10.1002/chem.200400361
Synthesis of the Glycopeptide Partial Sequence A80-A84 of Human Fibroblast Interferon
1985
The glycopentapeptide H-(GlcNAcβ1-)Asn-Glu-Thr-Ile-Val-OH (10) representing the partial sequence A80–A84 of human fibroblast interferon was synthesized using the newly developed allyl-ester protection of carboxy functions. The allyl esters, which are stable to acids and to bases, can be cleaved under very mild, neutral conditions using tris(triphenylphosphine)rhodium(I) chloride or tetrakis(triphenylphosphine)palladium(0) as a catalyst. This synthetic method opens up a preparative route to glycopeptide model structures of glycoproteins of high biological interest.
Orthometalation of Tris(3-sodium sulfonatophenyl)phosphine with Dirhodium(II) Acetate
1998
Tetraacetatodirhodium(II) reacts with tris(3-sodium sulfonatophenyl)phosphine (TPPTS) giving [Rh2(μ-OOCCH3)3{μ-(3-NaO3SC6H3)P(C6H4SO3Na-3)2}(HOOCCH3)]·6H2O (1) and [Rh2(μ-OOCCH3)2{μ-(3-NaO3SC6H3)P(C6H4SO3Na-3)2}2(HOOCCH3)]·12H2O (2). Their structures and properties have been studied by electronic, IR, and 31P{1H}, 1H, 1H{31P}, and 13C{1H} NMR spectroscopies. In compound 1, one of the acetate bridges is replaced by a phosphine ligand, orthometalated via the C2 carbon atom of the phenyl ring. One axial site of the Rh24+ core is occupied by a sulfonato group of the metalated ring and another one by a labile molecule of acetic acid. 1H NMR spectroscopy shows that chemical shifts of the aromatic…
Synthesis of Dirhodium(II) Complexes with Several Cyclometalated Thienylphosphines
2006
The thermal reaction of dirhodium tetraacetate with tris(3-thienyl)phosphine (3TP), diphenyl(3-thienyl)phosphine (3TPPh2), and diphenyl(2-thienyl)phosphine (2TPPh2) gives rise to mono-cyclometalated and bis-cyclometalated compounds; the latter can have a head-to-head (H−H) or head-to-tail (H−T) configuration. Bis-cyclometalated compounds with H−T configuration can be prepared in high yield under photochemical conditions or by combining irradiation with subsequent thermal treatment in acetic acid. The reactivity order of aromatic ring C−H activation is phenyl < 2-thienyl ≪ 3-thienyl, which leads to a selective activation of the thienyl ring. Thus, only one mono-cyclometalated compound is obt…
ChemInform Abstract: SYNTHESIS OF THE GLYCOPEPTIDE PARTIAL SEQUENCE A80-A84 OF HUMAN FIBROBLAST INTERFERON
1985
The glycopentapeptide H-(GlcNAcβ1-)Asn-Glu-Thr-Ile-Val-OH (10) representing the partial sequence A80–A84 of human fibroblast interferon was synthesized using the newly developed allyl-ester protection of carboxy functions. The allyl esters, which are stable to acids and to bases, can be cleaved under very mild, neutral conditions using tris(triphenylphosphine)rhodium(I) chloride or tetrakis(triphenylphosphine)palladium(0) as a catalyst. This synthetic method opens up a preparative route to glycopeptide model structures of glycoproteins of high biological interest.
Dirhodium(II) compounds with bridging thienylphosphines: studies on reversible P,C/P,S coordination.
2009
Monocyclometalated compound [Rh(2){(C(8)H(4)S)P(C(8)H(5)S)(2)}(CH(3)CO(2)H)(2)(O(2)CCH(3))(3)] (1 a) and bis-cyclometalated compound [Rh(2){(C(8)H(4)S)P(C(8)H(5)S)(2)}(2)(CH(3)CO(2)H)(2)(O(2)CCH(3))(2)] (2 a) have been isolated from the reaction of dirhodium tetraacetate and tris(2-benzo[b]thienyl)phosphine (2 BTP) using low acidic solutions. By contrast, in pure acetic acid the reaction of Rh(2)(O(2)CCH(3))(4) with 2 BTP and tris(2-thienyl)phosphine (2 TP), followed by replacement of the axial acetate ligands by chlorides, led to [Rh(2){(2-C(8)H(5)S)P(2-C(8)H(5)S)(2)}(2)Cl(2)(O(2)CCH(3))(2)] (3 b) and [Rh(2){(2-C(4)H(3)S)P(C(4)H(3)S)(2)}(2)Cl(2)(O(2)CCH(3))(2)] (5 b), respectively. These n…
Reaction of Tris(2-thienyl)phosphine with Dirhodium(II) Acetate. Orthometalation of a Heteroaromatic π-System and an Unusual Ring Rearrangement
2003
The reaction of tris (2-thienyl)phosphine (1) with dirhodium(II) acetate in a 9:1 refluxing toluene/ acetic acid mixture for 2 h leads to the formation of two metalated compounds. The structure of one of them contained two new orthometalated phosphines in a head-to-head arrangement, and, surprisingly, the metalated thiophene rings, but not the nonmetalated ones, were rearranged to a 3-thienyl structure. Both types of dirhodium compounds were assessed in a catalytic α-diazo ester transformation.
Orthometallation reactions of tris(p-methoxyphenyl)phosphine with dirhodium(II) tetraacetate
1998
Abstract Reactions of dirhodium(II)tetraacetate [Rh2(OAc)4] with tris(p-methoxyphenyl)phosphine (PMP) at 1:1 and 1:2 molar ratios yield, first appropriate adducts: [Rh2(OAc)4P(p-CH3OC6H4)3] (1a) and [Rh2(OAc)4{P(p-CH3OC6H4)3}2] (2a), and then orthometallated [Rh2(OAc)3{μ-(p-CH3OC6H3)P(p-CH3OC6H4)2}(HOAc)2] (1) and [Rh2(OAc)2{μ-(p-CH3OC6H3)P(p-CH3OC6H4)2}2(HOAc)2] (2) complexes, respectively. They have been characterized by spectroscopic methods. The molecular structure of 1 has been determined by the X-ray methods. Crystal data: space group P1, a=11.085(5), b=11.387(5), c=13.900(6) A, α=97.29(3), β=105.23(3), γ=91.93(3)°. In this compound The Rh–Rh distance is 2.421(1), Rh–P bond length 2.1…