Synthese,IR-Spektrum und Kristallstruktur von N,N'-Bis(trimethylsilyl)benzamidinium-tetrachloroferrat(III)

Synthesis, IR Spectrum, and Crystal Structure of N,N'-Bis(trimethylsilyl)benzamidinium Tetrachloroferrate(III) The title compound [C₆H₅? C(NHSiMe₃)₂][FeCl₄] is obtained by the reaction of FeCl₃ with N,N,N'-tris(trimethylsilyl)benzamidine in the presence of tetrahydrofurane, forming yellow, moisture sensitive crystals. The compound is characterized by its IR spectrum as well as by an X-ray structure determination. Space group P2₁/n, Z = 8, 5974 independent observed reflexions, R = 0.066. The lattice dimensions are at ?70°C: a = 2110.7, b = 1109.5, c = 2120.4 pm; β = 111.17º. The compound forms ion pairs, in which the H atoms of the amidinium cation are coordinated with one chlorine ligand of the FeCl₄^? ion in a chelating manner.     

Übergangsmetallkomplexe mit Schwefelliganden. XLIV. Ruthenium(II)-Komplexe mit dem sterisch anspruchsvollen Thioether-Thiolat-Liganden ‚buS4’︁2− (= 1,2-Bis(3,5-di(tertiärbutyl)-2-mercaptophenylthio)-ethan (2-)) sowie den Koliganden PPh3, PMe3, CO,NH3 und N2H4

Transition Metal Complexes with Sulfur Ligands. XLIV. Ruthenium(II) Complexes with the Sterically Demanding Thioether-thiolate Ligand ?^buS₄’?^2?(= 1,2-Bis(3,5-di(tertiarybutyl)-2-mercaptophenylthio) ethane (2-)) and PPh₃, CO, PMe₃, NH₃, and N₂H₄ Coligands The coordination properties of the sterically demanding thioether-thiolate ligand ‘^buS₄’^2? (= 1,2-Bis(3,5-di(tertiarybutyl)-2-mercaptophenylthio)ethane (2-)) towards Ruthenium were investigated. [Ru(PPh₃)₂ (‘^buS₄’)], 1 , was obtained from [RuCl₂(PPh₃)₃] and ‘^buS₄’? Li₂. One PPh₃ ligand in 1 is labile towards substitution and can be exchanged by L ? CO ( 2 ), PMe₃ ( 3 ), or NH₃ ( 5 ) yielding [Ru(L)(PPh₃)(‘^buS₄’)]. The PMe₃ complex [Ru(PMe₃)₂(‘^buS₄’)], 4 , is thermically inert as well as 2, 3 , and [Ru(CO)₂(‘^buS₄’)], 6 , which was obtained from [RuCl₂(CO)₃THF] and ‘^buS₄’? Li₂. Considering the thermical reaction inertness of 6 , its fast reaction with N₂H₄ yielding [Ru(N₂H₄) (CO) (‘^buS₄’)], 7 , is remarkable; the reaction probably takes place via 19e- intermediates. All ‘^buS₄’ complexes are better soluble in organic solvents than the corresponding [Ru(‘S₄’)] parent compounds, their ν(CO)frequencies or ³¹PNMR shifts, however, are nearly identical, allowing the conclusion that the influence of the t-butyl groups is topological and not electronic. All now complexes were characterized by elemental analyses as well as IR, NMR, and mass spectroscopy.     

Initiation of Protein Synthesis with Non-Canonical Amino Acids In Vivo

By transplanting identity elements into E. coli tRNA^fMet, we have engineered an orthogonal initiator tRNA (itRNA^Ty2) that is a substrate for Methanocaldococcus jannaschii TyrRS. We demonstrate that itRNA^Ty2 can initiate translation in vivo with aromatic non-canonical amino acids (ncAAs) bearing diverse sidechains. Although the initial system suffered from low yields, deleting redundant copies of tRNA^fMet from the genome afforded an E. coli strain in which the efficiency of non-canonical initiation equals elongation. With this improved system we produced a protein containing two distinct ncAAs at the first and second positions, an initial step towards producing completely unnatural polypeptides in vivo. This work provides a valuable tool to synthetic biology and demonstrates remarkable versatility of the E. coli translational machinery for initiation with ncAAs in vivo.     

Conjugate addition reactions of alpha-aminoalkylcuprates with alpha, beta-alkenyl-, alpha,beta-alkynyl-, alpha,beta-beta,gamma-allenyl-, and alpha,beta-gamma,delta-dienyl carboxylic acid derivatives, nitriles, and sulfoxides

alpha-Aminoalkylcuprates prepared from alpha-lithio carbamates and CuCN.2LiCl participate in 1,4-addition reactions with alpha, beta-unsaturated esters, thiol esters, imides, and nitriles in poor to excellent yields depending upon the electron-withdrawing substituent and the substitution pattern of the unsaturated substrate. These reagents also undergo conjugate addition reactions with alpha,beta-alkynyl esters, sulfoxides, and nitriles and with alpha,beta-beta,gamma-unsaturated allenyl esters. Excellent stereocontrol is achieved in the conjugate additions of alpha-aminoalkylcuprates to the allenyl esters, while poor stereoselectivity results in the conjugate additions to the alkynyl derivatives. Deprotection and cyclization of the alkynyl adducts affords pyrrolin-2-ones, while similar treatment of the allenyl adducts affords 4-alkylidine- pyrrolidin-2-ones and pyrrolizidinones.