Winfried Hoffmüller

Catalytic Formation of Oligopeptides from α-Amino Acid Esters with (p-Cymene)ruthenium(II) Complexes

Consecutive addition of one-equivalent portions of glycine ethyl ester to [(p-cymene)Ru(GGGOMe−H+)Cl] leads to considerable amounts of (tetra- to nonapeptide)ruthenium complexes in a one-pot reaction, in which the (p-cymene)RuCl fragment acts as a catalyst. The analogous reaction with alanine methyl ester affords AGGG and AAGGG complexes as the main products. The course of these metal-catalyzed peptide oligomerizations has been followed by mass spectrometry. The synthesis and characterization of the pentapeptide complex [(C6Me6)Ru(GGGGGOMe−H+)] is reported.

Metal Complexes of Biologically Important Ligands, CVII [1], Formation of Tris(pentamethylcyclopentadienyl-μ-L-prolinato-iridium) Tris(trifluoromethanesulfonate) with Chiral Self Recognition

The structure of the title complex consists of [Ir3(C5Me5)3(L-prolinate)3]3+ complex cations and CF3SO3- anions. Each iridium atom is coordinated in a distorted tetrahedral manner by one cyclopentadienyl group, two carboxylate O atoms and the prolinate N atom. The iridium atoms are bridged by the carboxylate groups. Each of the three stereogenic iridium atoms has the same (S) configuration, i. e. the trimerization of the [Ir(C5Me5)(L-prolinate)]+ fragment occurs with chiral self recognition.

Halbsandwich-Komplexe von (S)-1-Amino-2-(methoxymethyl)-pyrrolidin (SAMP)

The chloro-bridged complexes [Cp*MCl2]2 (Cp* = C5Me5, M = Ir, Rh), [(p-cymene)RuCl2]2, [(C6Me6)RuCl2]2, and [(Et3P)PdCl2]2 react with SAMP by cleavage of the chloro bridges to give the corresponding monomeric h1-SAMP complexes. The x-ray structural detns. of [cyclic] Cp*RhCl2NH2N(CH(CH2OMe)(CH2)3) and [cyclic] [(C6Me6)RuCl2NH2N(CH(CH2OMe)(CH2)3)] show coordination of the amino group in these complexes. From the chloro-bridged complexes, SAMP and sodium a-ketocarboxylates Schiff base N,O-chelate complexes were obtained. The structure of the [cyclic] [Cp*(Cl)IrO2CCMe2:N(NCH(CH2OMe)(CH2)3)] complex with coordination of the carboxylate-O and the imine-N atom was detd. by x-ray diffraction. [on SciFinder (R)]

Metallkomplexe mit biologisch wichtigen Liganden, CXXVIII [1], Palladium(II)-Komplexe mit deprotonierten Peptidestern als N,N′-Chelatliganden / Metal Complexes with Biologically Important Ligands, CXXVIII [1]. Palladium(II) Complexes with Deprotonated Peptide Esters as N,N′-Chelate Ligands

Reactions of chloro bridged palladium compounds with di- and tripeptide esters give (Et3P)(Cl)2Pd(NH2CHR1CONHCHR2CO2CH3) and the N,N′-chelate compounds (Et3P)- (Cl)Pd(NH2CH2CONCHR1 CO2R2), [C6H4CH 2NMe2(C,N)]Pd(NH2CH2CONCH2CO2Et) and (Et3P)Pd(gly-gly-glyOMe-2H+). The structure of (Et3P)(Cl)Pd(gly-alaOMe-H+) was determined by X-ray diffraction analyses. Attempts to form open chain peptides from α-amino acid ester in the coordination sphere of palladium(II) are reported

Metallkomplexe mit biologisch wichtigen Liganden, CLXI [1]. Halbsandwich-Komplexe mit tert-Leucin, Dipeptiden, Pentaglycin und Glutathion als Liganden / Metal Complexes with Biologically Important Ligands, CLXI [1]. Halfsandwich Complexes with tert-Leucine, Dipeptides, Pentaglycine and Glutathione

Reactions of L-tert-Leucine (tert-butylglycine), tert-leucine methyl ester, GlyValOMe, and Leu- AlaOMe with the chloro-bridged complexes [Cp*IrCl2]2, [(p-cymene)RuCl2]2 or [(C6Me6)RuCl2]2 in the presence of NaOMe give the complexes [Cp*Ir(Cl)NH2CH(R)CO2] (1), [(p-cymene)Ru(Cl)- NH2CH(R)CO2] (2), Cp*Ir(Cl2)[NH2CH(R)CO2Me] (5), {(C6Me6)Ru(Cl)[NH2CH2CONHCH(R)- CO2Me]}+Cl− (6), [Cp*Ir(Cl)NH2CH2CONCH(R)CO2Me] (7), [Cp*Ir(Cl)NH2CH(CH2CHMe2)- CONCH(R)CO2Me)] (8), and Cp*Ir(Cl2)[NH2CH2CONHCH(R)CO2Me) (9). With pentaglycine the complexes [Cp*Ir(Cl2)(pentaglycinate+Na+)] (10) and [(C6Me6)Ru(pentaglycineOMe- H+)] (11) could be isolated. Coordination of one equivalent of the S-protected tripeptide glutathione to [Cp*Ir(Cl)] and to [(C6Me6)Ru(Cl)] was observed. Some in situ prepared (p-cymene)Ru complexes with deprotonated dipeptide esters were tested as catalysts and the complex [(p-cymene)Ru(Cl)(NH2CH(CHMeEt)NCH (CHMe2)CO2tert-Bu)] gave a yield of 73% and moderate entantiomeric excess (36% ee) in the transfer hydrogenation of acetophenone to 2-propanol.

Metallkomplexe mit biologisch wichtigen Liganden, CXIX [1]. Ein tetraedrischer Zink-Komplex (L-terf-Leucin)2ZnCl2 mit Carboxylat-koordiniertem L-terf-Leucin in der / Zwitterform Metal Complexes of Biologically Important Ligands, CXIX [1]. A Tetrahedral Zinc Complex (L-terf-Leucine)2ZnCl2 of Carboxylate Coordinated L-terr-Leucine in the Zwitterionic Form

From an aqueous solution of ZnCl2 and L-terMeucine the complex (L-terr-Leucine)2ZnCl2 · 2 CH3OH with a distorted tetrahedral structure is formed in which, according to an X-ray structure analysis, the zwitterionic form o f the amino acid is coordinated through the carboxylate group

Metallkomplexe mit biologisch wichtigen Liganden, CXXXVII [1]. Halbsandwich-Komplexe mit N, O-Chelaten und Schiff-Basen von β-Aminosäuren/ Metal Complexes of Biologically Important Ligands, CXXXVII [1]. Halfsandwich Complexes with N, O-Chelates and Schiff Bases of β-Amino Acids

Abstract β-Phenylalanine forms with chloro bridged complexes the chiral N, O-chelates Cp*Ir(Cl)(NH2CH(Ph)CH2CO2) and (p-cymene)Ru(Cl)(NH2CHPhCH2CO2) as mixture of two diastereoisomers. Similarly the palladium(III) and platinum(II) complexes (Et3P)(Cl)M(NH2CH(Ph)CH2CO2) (M = Pd, Pt) were obtained. Schiff base complexes (arene)(Cl)M(O2CC(R)=N-CH(R)CH(R)CH2CO2CH3) (arene = Cp*, p-cymene; M = Ir, Ru) were synthesized from the chloro-bridged compounds, 2-oxocarboxylates and β-alanine or β-phenylalanine methylester. The Cp*Ir complex with a tridendate dianionic Schiff base generated from pyruvate and β-phenylalaninate is obtained as a single isomer. Cp*Ir(Cl) forms a complex with an N, O-bidentate Schiff base ligand from glycinate and acetylacetic ethyl ester.