Free Imine Research Articles

Ritter reaction on terpenoids. III. Stereospecific preparation of bicyclic [3.3.1] substituted piperidines

Treatment of chiral monoterpenes with different nitrile compounds in the presence of perchloric acid affords (1S,5R,8R) 8-alkyl(aryl)-2-alkyl(aryl)-2,4,4,8-tetramethyl-3-azabicyclo[3.3.1]non-2-ene or the corresponding (1R,5S,8S) enantiomer. The respective free imines yield optically pure piperidine derivatives when treated with reducing agents (NaBH 4, NaCNBH 3).

Separation of Ring Polar and Resonance Effects on the Rate and Equilibrium Constants for Methoxide Ion-Promoted Addition of Methanol to N-Benzylideneanilines Substituted at the Benzylidene Moiety

Rate and equilibrium constants for the title reaction (α-amino ether formation) at 25 o C in methanol are reported for (16) N-benzylideneani- lines (BAs) substituted at the benzaldehyde moiety. In contrast to a previous report dealing with BAs substituted at the aniline residue, it is shown that an uncatalyzed pathway competes with the methoxide ion- catalyzed reaction, these two processes corresponding to rate-limiting attachment of the lyate ion to the C=N bond of iminium ion and free imine, respectively. For the latter reaction pathway, the lifetimes of the amide-ion intermediates are long enough to allow a stepwise mecha- nism

The schiff base between pyridoxal‐5′‐phosphate (PLP) and hexylamine. Formation of the unprotonated form of the imine by reaction of the unprotonated PLP and free amine

AbstractElectrochemical and spectrophotometric studies of the pyridoxal‐5′ ‐phosphate hexylamine Schiff base (PHSB) in strongly basic media were carried out. The equilibrium constant and rate constants of the formation and hydrolysis of the unprotonated imine from the unprotonated pyridoxal‐5′ ‐phosphate and free amine were determined by linearscan cyclic voltammetry. The acid‐base dissociation constant of the imine group was obtained by spectrophotometric measurements. Absorption bands for the free imine and the conjugate acid are characterized by a log‐normal distribution. These studies are for general application to the quantitative characterization of non‐enzymatic model compounds.

ChemInform Abstract: Synthesis and Characterization of the First Borane Adducts and Boron Cations of Some N‐Alkyl and N‐Aminotriphenylphosphoranimines.

Abstract The first borane adducts of N-alkyl and N-aminotriphenylphosphoranimines, Ph3P[dbnd]N—R, were prepared by two different general synthetic methods. The first method involved displacement of THF (tetrahydofuran) from THF-borane by the free imines, and the second employed the reaction of LiBH4 with iminium bromides, Ph3P[dbnd]N(R)HBr, in diethyl ether. Imine boranes, Ph3P[dbnd]N(R)BH3, were synthesized where R [dbnd] methyl, ethyl, n-propyl, isopropyl, isobutyl, t-butyl. dimethylamino, phenylamino, and methyl, phenylamino as the nitrogen attached groups. Symmetrical boron cations, (Ph3P[dbnd]NR)2, BH2 +, where R = methyl, ethyl, and n-propyl, were synthesized by displacement of iodide from in-situ generated iodoborane adducts, Ph3P[dbnd]N(R)BH2I, by the free imines. An attempt to form an unsymmetrical boron cation from (CH3)3 NBH2I and Ph, P[dbnd]N(n-C3H7) resulted only in a mixture of the corresponding symmetrical boron cations. Physical, chemical and spectral properties of the borane adducts and b...

SYNTHESIS AND CHARACTERIZATION OF THE FIRST BORANE ADDUCTS AND BORON CATIONS OF SOME N-ALKYL AND N-AMINOTRIPHENYLPHOSPHORANIMINES

Abstract The first borane adducts of N-alkyl and N-aminotriphenylphosphoranimines, Ph3P[dbnd]N—R, were prepared by two different general synthetic methods. The first method involved displacement of THF (tetrahydofuran) from THF-borane by the free imines, and the second employed the reaction of LiBH4 with iminium bromides, Ph3P[dbnd]N(R)HBr, in diethyl ether. Imine boranes, Ph3P[dbnd]N(R)BH3, were synthesized where R [dbnd] methyl, ethyl, n-propyl, isopropyl, isobutyl, t-butyl. dimethylamino, phenylamino, and methyl, phenylamino as the nitrogen attached groups. Symmetrical boron cations, (Ph3P[dbnd]NR)2, BH2 +, where R = methyl, ethyl, and n-propyl, were synthesized by displacement of iodide from in-situ generated iodoborane adducts, Ph3P[dbnd]N(R)BH2I, by the free imines. An attempt to form an unsymmetrical boron cation from (CH3)3 NBH2I and Ph, P[dbnd]N(n-C3H7) resulted only in a mixture of the corresponding symmetrical boron cations. Physical, chemical and spectral properties of the borane adducts and b...

Ligand exchange reactions in cyclopalladated complexes of benzylideneanilines. Crystal structure of [Pd(C6H4CHNC6H5)Br(PPh3)2

The ligand exchange reactions between [{[graphics omitted]C6H5)(O2CMe)}2] and the free imines p-RC6H4CHNC6H5(R = H, Cl, NMe2, or NO2)(N[graphics omitted]CH) in acetic acid have been studied. The substitution process is favoured when the incoming ligand contains electron-withdrawing substituents. From the results obtained a new mechanism involving a bis-cyclometallated complex ([graphics omitted]P[graphics omitted])] as intermediate is proposed. The dimeric cyclopalladated compounds are obtained by metallation of the imines by Pd(O2CMe)2; by reaction with phosphines PR′3 and LiBr, [[graphics omitted]C6H5)Br(PR′3)] and [Pd(p-RC6H3CHNC6H5)Br(PR3′)2] are formed (R′= Ph or Et). All the compounds have been fully characterized and their 1H and 13C n.m.r. spectroscopic data recorded. The molecular structure of [Pd(C6H4CHNC6H5)Br(PPh3)2] has been determined by a single-crystal X-ray analysis. The crystals are monoclinic, space group P21/a, a= 17.427(3), b= 24.790(4), c= 10.424(2)Å, β= 98.91(2)°, and Z= 4; R= 0.053 for 6 579 reflections. The palladium atoms are five-co-ordinated, the Pd–N distance being 2.710(6)Å.

1a,11b‐dihydrobenz[5,6]anthr[1,2‐B]azirine. A non k‐region polycyclic arene imine

AbstractThe synthesis of the title compound 9 is described. Benz[a]anthracene 8,9‐oxide (6) was reacted with sodium azide in aqueous acetone and the trans‐9‐azido‐8,9‐dihydrobenz[a]anthr‐8‐ol (7), so formed, was cyclized by tri‐n‐butylphosphine. Attempts to dehydrogenate 10,11‐dihydrobenz[a]anthracene 8,9‐imine (4) with DDQ or by allylic bromination followed by base assisted dehydrobromination was unsuccessful. The N‐tosyl derivative of 4, prepared from the free imine, N,O‐bis(trimethylsilyl)acetamide and tosyl chloride underwent rapid aziridine‐ring cleavage by the silylating agent to give trans‐8,9,10,11‐tetrahydro‐8‐(4‐methyl)benzensulfon‐amido‐9‐ [(trimethyl)oxy]benz[a]anthracene (10).

Polyhalogenoaromatic compounds. Part XVII. Synthesis of arylpentachlorophenyl ketone imines and 2,4-diaryl-5,6,7,8-tetrachloroquinazolines by the reaction of pentachlorophenyl-lithium with nitriles

The addition of pentachlorophenyl-lithium to aromatic nitriles gives N-lithio-arylpentachlorophenylketone imines. Hydrolysis of the N-lithio-imines gives the free imines as mixtures of syn- and anti-isomers, and reaction with dimethyl sulphate gives the N-methyl derivatives.With an excess of the nitrile, pentachlorophenyl-lithium give 2,4-diaryl-5,6,7,8-tetrachloroquinazolines.

Benzoquinone imines. Part II. Hydrolysis of p-benzoquinone monoimine and p-benzoquinone di-imine

Kinetic studies of the hydrolysis of p-benzoquinone monoimine, over the pH range 2–10, have shown that the reaction exhibits first-order kinetics over the whole pH range. The pH dependence indicates a rate-controlling step involving the reaction of both the free imine and its protonated form with water, the latter being 1·8 × 103 more reactive than the former. The reaction was found to be catalysed by phosphate ions. Similarly the hydrolysis of p-benzoquinone di-imine involves reaction of the free base and its mono- and di-protonated forms with water. Phosphate ions do not catalyse the reaction, but, in the pH range 5·5–8, polymerisation of the di-imine occurs as a significant side-reaction, even at low concentrations.