M. M. Shtern

Urea as ammonia equivalent in aryl halides amination catalyzed by palladium complexes

Urea reaction with nonactivated aryl bromides and chlorides under catalysis with palladium complexes led to the formation in 65–95% yield of triarylamines from para-and meta-substituted aryl halides and of diarylamines from ortho-isomers.

Unexpected formation of [Z-PhCFCFRe2(CO)9]Na in the reaction of [Re(CO)5]Na with α,β,β-trifluorostyrene

Abstract The reaction of [Re(CO)5]Na with α,β,β-trifluorostyrene follows two concurrent pathways: nucleophilic vinylic substitution forming Z-PhCFCFRe(CO)5 and radical-chain process producing Z-[PhCFCFRe(CO)4Re(CO)5]Na. The intermediacy of metal carbonyl radicals in the radical process is evident from the fact that tertiary phosphines or an ‘electron trap’ inhibit, and Re2(CO)10, induce the production of Z-[PhCFCFRe(CO)4Re(CO)5]Na.

N,N′-bis(ortho-acylaryl)diaza-18-crown-6 ethers: Synthesis, complexation in solution, and crystal structure of the complex with lead perchlorate

Two new lariat ethers were obtained from N,N′-diaryldiaza-18-crown-6 (Ar = 2-formyl-4-methylphenyl (II) and 2-benzoyl-4-methylphenyl (III)). In the ethers obtained, the carbonyl O atoms act as additional electron-donating sites. Complexation of lariat ethers II and III with metal cations in solution was studied by 1H NMR spectroscopy (acetone-d6, methanol-d4). The stability constants of the resulting complexes were determined. For lariat ether III and its complexes, the magnetic anisotropy of the benzoyl groups substantially influences the chemical shifts of the protons of the macrocycle. The stability of the complexes increases from ether II to III and in the order K+ < Ba2+ < Pb2+. Complexes with La3+ were not obtained. The complex of lariat ether II(L) with Pb(ClO4)2, [PbL(H2O)](ClO4)2 · H2O, was characterized by X-ray diffraction. The Pb2+ cation is in the cavity of the lariat ether and is coordinated by the formyl O atoms on one side of the macrocycle plane and by the water molecule on the other side (C.N. 9).

13C and19F NMR study of α,β-difluorostyryl derivatives of transition metal carbonylates. A method of signal assignment based on the carbon—fluorine spin-spin coupling constants

The13C and19F NMR spectra ofZ- andE-isomers of β-X-substituted α,β-difluorostyrenes (X=F, Cl, CpFe(CO)2, Re(CO)5, Re2(CO)9Na) were studied. Direct and long-range (across 1–5 bonds) spin-spin coupling constants and the (13C−12C) isotope shifts in the19F NMR spectra were determined. The study of the13C satellites in the19F NMR spectra of substituted difluorostyrenes permitted assignment of the13C NMR signals of the vinylic carbon atoms. Similarly, the signals in19F NMR spectra were assigned based on coupling constants of fluorine withipso-carbon. These assignments were found to be in good agreement with the data available from the literature (X=F, Cl). The developed approach was applied to the elucidation of the structure ofZ−PhCF=CClFe(CO)2Cp.

Amination of meso-bromophenyl(polyalkyl)porphyrins: Synthesis of porphyrins containing a hydroxypiperidine fragment

Abstract5,15-Bis(4-bromophenyl)-2,8,12,18-tetraethyl-3,7,13,17-tetramethylporphyrin and 5-(4-bromophenyl)-13,17-dibutyl-2,3,7,8,12,18-hexamethylporphyrin were synthesized, and their palladium-catalyzed amination with a number of cyclic secondary amines, including hydroxypiperidines, was studied [Pd(OAc)2, ligand, THF or dioxane, t-BuONa, 80–100°C]. The reactions of the meso-bromophenylporphyrins with piperidine and morpholine gave the corresponding amination products in quantitative yield. The amination with hydroxypiperidines required excess amine (3 equiv per bromine atom) and excess base (6–8 equiv) and was accompanied by formation of hydrodebromination products; in the reactions with the bis(bromophenyl)derivative, mixed products resulting from amination at one phenyl group and reductive debromination at the other were also formed. The yields of the amination products varied from good {75–50% in the reactions with 4-hydroxypiperidine and trans-3-hydroxy-4-[4-(2-fluorophenyl)piperazin-1-yl]piperidine} to moderate (20–50%, 3-hydroxypiperidine) and poor [11–25%, trans-3,4-dihydroxypiperidine and trans-3-hydroxy-4-(4-hydroxypiperidin-1-yl)piperidine].