Microwave-induced clay-catalyzed ring opening of N-tosylaziridines: a green approach to achiral and chiral diamines

N-Tosylaziridines react efficiently with amines in the presence of Montmorillonite K-10 as catalyst under microwave irradiation in solvent-free conditions to yield the corresponding achiral and chiral diamines regio- and stereoselectively, in a few minutes and in high yields.     

Vapour pressures and excess functions of N, N, N′, N′-tetramethylalkanediamine + cyclohexane. A group contribution study of the N---N proximity effect

The vapour pressuresof liquid cyclohexane + N, N, N′, N′-tetramethylalkanediamine, (CH₃)₂ N(CH₂)_uN(CH₃)₂ (u = 1,2) + cyclohexane mixtures were measured by a static method between 303.15 and 343.15 K at 10 K intervals. The excess molar enthalpies at 303.15 K were also measured.

The molar excess Gibbs energies, calculated from the vapour-liquid equilibrium data, and the molar excess enthalpies compare satisfactorily with group contribution (DISQUAC) predictions.

The proximity effect of N atoms produces a regular decrease of the interactional parameters.     

Synthesis and Characterization of [(1,4‐diamine)dichloro]platinum(II) Compounds Preliminary Studies on their Biological Activity

Two 1,4‐diamine ligands were synthesized having 1,2‐bis(aminomethyl)‐cyclohexane and 1,2‐bis(aminomethyl)‐benzene structures. The two ligands have different electron density in the six‐membered ring: a cyclohexane versus a phenyl ring. The organic synthesis of the ligands was carried out by synthetic pathways of seven and four steps, respectively, starting from 1,2,3,6‐tetrahydrophthalic anhydride and diethyl phthalate. The coordination of platinum to these ligands afforded platinum(II) complexes which are analogue to the clinical drug cisplatin but form a seven‐membered chelate ring. The interaction of the platinum compounds with DNA was studied in order to know the relationship between the electron density of ligands and their capability to chelate DNA, by using three techniques: Circular Dichroism, Agarose Gel Electrophoresis and Atomic Force Microscopy. The degree of interaction of both compounds with DNA was slightly different, but both complexes showed a cisplatin‐like behaviour and are promising candidates to follow an extensive study of their cytotoxic activity.     

New developments in zinc-catalyzed asymmetric hydrosilylation of ketones with PMHS

The influence of structural modifications of the diamine ligand and the ZnR₂ precursor in the [ZnR₂-diamine]-catalyzed asymmetric hydrosilylation of prochiral ketones with PMHS in aprotic medium is reported. A new diamine ligand giving up to 91% ee in the reduction of acetophenone is described. The scope of this reduction system has been investigated using variously functionalized ketones and some deactivation pathways have been identified.     

Integrating chemosensors for amine-containing compounds into cross-linked dendritic hosts

Trifluoroacetylazo dye 1, a known chemosensor for amines, has been integrated into cross-linked dendrimer hosts. Thus, boronic acid 16 was linked to iododye 9 via a Suzuki coupling reaction. In situ deprotection and alkylation with dendrons 3 and 4, containing 8 homoallyl or allyl ether groups, respectively, afforded dendrons 18 and 19 with chemosensor units at their focal point. Conversion of 18 (19) to the bis-imine of butane 1,4-diamine, extensive cross-linking via the ring closing metathesis reaction with Grubbs catalyst 25, and hydrolysis produced dendrimer hosts 28 and 29. Host-guest studies with a small library of amines and alcohols showed 28 and 29 to selectively signal certain diamines but not due to template mediated imprinting.     

Synthesis of substituted 1,1′-diaminoferrocenes from cyclo-2-pentene imines

Condensation of anilines and primary aliphatic amines with 3,4-diphenylcyclo-2-pentenone leads to the corresponding diphenylcyclopentene imines in good yields of 72-90%. Deprotonation of these aminocyclopentadiene tautomers and reaction with FeCl₂ leads to the synthesis of the respective 1,1′-diamino-3,3′,4,4′-tetraphenylferrocenes. Yields increase from 33% to 65% with a decrease in the steric bulk of the amine substituent. The observation that a successful conversion requires two equivalents of base is conceived on the basis of the discussed reaction mechanism. The molecular structure of 1,1′-dianilino-3,3′,4,4′-tetraphenylferrocene (3a), which was determined by single crystal X-ray analysis reveals a trans coordination of the two amine moieties with respect to the central Cp-Fe-Cp axis of the ferrocenyl backbone.     

Double photoionisation spectra of small molecules and a new empirical rule for double ionisation energies

Complete double photoelectron spectra are presented for 18 small molecules where the location of charges in the cations and dications is relatively clearly defined. The data demonstrate the importance of a coulombic repulsion contribution to the double ionisation energies. Examination of data for a wide range of molecules leads to a new empirical rule to calculate double ionisation energies from the molecules’ single ionisation energies and maximum dimensions. Where single and double ionisation energies are known the rule allows the deduction of plausible intercharge distances.     

Spectroscopic and thermodynamic studies on solvatochromic nickel(II) complexes

Summary The solvatochromic and thermochromic behaviour of a series of mixed Ni(II) complexes with unsubstituted and substituted -diketones and diamines in the solvents 1,2-dichloroethane (DCE), acetonitrile (An), acetone (AC),n-butanol (n-BuOH), formamide (FA), N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO) and pyridine (PY) has been studied and characterized on the basis of electronic spectra. Spectrophotometric methods have been used to evaluate equilibrium constants and their enthalpic and entropic terms for the formation of Ni(-dik)(diam)L ⁺ and Ni(-dik)(diam)L ₂ ⁺ . Increasing donor strength of the donor-solvents (L) and (or) increasing electronwithdrawing parameters of the substituents at the -diketone and the diamine ligands lead to increasing formation constants, paralleled by relative increase in the stability of the five-coordinated species Ni(-dik)(diam)L ⁺. The results are discussed in terms of the extended donor-acceptor concept.On leave of absence from the Faculty of Education, Ain Schams University, Roxy, Cairo, Egypt     

Enantioselective addition of aryllithium reagents to aromatic imines mediated by 1,2-diamine ligands

A variety of optically enriched amines have been obtained by addition of aryllithium reagents to aromatic imines using N,N′-tetramethylcyclohexane-1,2-diamine as chiral ligands. Enantiomeric excesses up to 90% could be obtained.     

<Emphasis Type="Italic">o</Emphasis>-Phenylenediamine as a New Catalyst in the Highly Regioselective Conversion of Epoxides to Halohydrins with Elemental Halogens

Summary. The regioselective ring opening of epoxides using elemental iodine and bromine in the presence of o-phenylenediamine as a new catalyst affords vicinal iodo alcohols and bromo alcohols in high yields. The major advantages of this method are versatility, high regioselectivity, a cheap and commercially available catalyst, mild and neutral reaction conditions, and short reaction times. Fourier transform Raman spectroscopy was used to study the reaction of iodine with o-phenylenediamine. The results indicate that the complex [(Diamine)I]⁺·I₅^– is formed, and we suggest that the major nucleophile is the pentaiodide ion. This bulky nucleophile has a fundamental role in the high regioselectivity observed attacking the less sterically hindered epoxide carbon.