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The photoreversible transportation of Zn2+ions across an interface using photochromic substitutedspirobenzopyrans has been demonstrated. The inclusion of strategically placed sterically influencing 3′methyl3band 3spirocyclohexyl3cgroupings is investigated and compared to the unsubstituted analogue 3a. Significant control over the spiropyran ringopening↔closing reaction, and hence Zn2+ion transportation has been realised. Additionally, the spiropyran ringopening↔closing reactions of two skeletally identical spirobenzopyrans 4and 5, but possessing “electronicallymodifying” 5trifluoromethylsubstitutents have been studied by 1H NMR spectroscopy: this has enabled us to realise the additional biasing, on the ringopening↔closing process, excerpted on these systems through both selectively placed, inductively controlling functionalgroup substitution andor, simultaneously, sterically influencing group substitution. © WileyVCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008

The reversible photochemical ion chelation of the newly synthesised substituted N,N′-bis(spiro[1-benzopyran-2,2′-indolyl])diazacrown systems 15a–c and the subsequent molecular electronic control of this process using appropriately placed substituent groups on the spiro-benzopyran skeleton is reported. The principle of molecular electronic control of ion chelation is demonstrated by comparing the behaviour of the newly synthesised nitro-substituted and pyrido-annulated spiro-benzopyran system 9b with that of the unsubstituted compound 9a. Electronic substituent control over ion chelation is then exemplified for the new N,N′-bis(5′-nitrospiro[1-benzopyran-2,2′-indolyl])diazacrown system 15c and further exemplified for the corresponding 5′-trifluoromethyl derivative 15b, which contains the photochemically more robust trifluoromethyl group. The crown system 15a, unsubstituted in the spiro-indole moiety, is also reported. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Steric buttressing has been used to effect ene reactions involving conjugated enoic esters under relatively mild conditions and with improved control of observed stereoselectivities.

Ytterbium and neodymium have been shown to exhibit sensitised emission following excitation of pyrene chromophores. Sensitised emission is demonstrated in self-assembled complexes and in azamacrocycle derivatives bearing pendent pyrene groups. Energy transfer in these systems is dependent on the nature of the link between the ligand and the complex.

Ytterbium and neodymium have been shown to exhibit sensitised emission following excitation of pyrene chromophores. Sensitised emission is demonstrated in self-assembled complexes and in azamacrocycle derivatives bearing pendent pyrene groups. Energy transfer in these systems is dependent on the nature of the link between the ligand and the complex.

A new europium(III) chelate, which uses the 2,2'∶6',2"-terpyridyl chelating group as sensitizer, has been synthesized and its spectral properties investigated. The chelate, which can incorporate an isothiocyanate group for biological labelling, has proved useful in time resolved fluorescence studies and for delayed fluorescence resonance energy transfer (DEFRET).

The kinetics of the inactivation of beta-lactamase I from Bacillus cereus 569 by preparations of 6 alpha-bromopenicillanic acid showed unexpected features. These can be quantitatively accounted for on the basis of the inactivator being the epimer, 6 beta-bromopenicillanic acid. At pH 9.2, the rate-determining step in the inactivation is the formation of the inactivator. When pure 6 beta-bromopenicillanic acid is used to inactivate beta-lactamase I, simple second-order kinetics are observed. The inactivated enzyme has a new absorption peak at 326 nm. The rate constant for inactivation has the same value as the rate constant for appearance of absorption at 326 nm; the rate-determining step may thus be fission of the beta-lactam ring of 6 beta-bromopenicillanic acid. Inactivation is slower in the presence of substrate, and the observed kinetics can be quantitatively accounted for on a simple competitive model. The results strongly suggest that inactivation is a consequence of reaction at the active site.

Significant promotion of both unactivated and activated carbocyclic Diels–Alder cyclisations across the furan ring system is observed on changing from an organic to an aqueous solvent system.

The inactivation of beta-lactamase I by preparations of 6alpha-bromopenicillanic acid showed unexpected kinetic features that indicated that the active species was the 6beta-epimer. Samples containing 6beta-bromopenicillanic acid have been synthesized and shown to inactivate the enzyme in a rapid stoicheiometric reaction.

The preparation of 2-bromomethyl-8-(2,2-dimethylpropanoyloxyquinoline) is described and its use as a synthon for the incorporation of 8-hydroxyquinoline units into aza-crowns is exemplified.

The bulky trityl steric buttress is used to effect an intramolecular, uncatalysed ene reaction that operates at room temperature, whilst smaller buttresses require heat.

Incorporation of 9(10H )-acridone as a chromophore into a seven-coordinate chelating ligand allows observation of sensitised luminescence from the europium(III) complex, even with excitation wavelengths greater than 410 nm.

The phenanthridinium-linked terbium complex [4Tb.5] serves as a novel probe for DNA duplexes.

For Abstract see ChemInform Abstract in Full Text.

For Abstract see ChemInform Abstract in Full Text.

For Abstract see ChemInform Abstract in Full Text.

For Abstract see ChemInform Abstract in Full Text.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Heating of the oxime tosylate (II), generated from 2‐methylthiobenzoic acid (I), in the presence of an acid results in cyclization, producing ethyl 4‐oxo‐1,2‐benzothiazine‐3‐carboxylate (III).

The title glycoside fragment (VII) represents the D,E,F ring system of the anticancer antibiotic nogalamycin (XII).

The racemic furylethanol (I) is converted to the ketone (III), which undergoes reduction to give a 13:1 mixture of the epimeric allylic alcohols (V) and (VI).

As an approach to the heterocyclic part of the antibiotic bicyclomycin the reaction of pyrazines, e.g. (III), with singlet oxygen is carried out.

The alkylated and deprotected mono imino ether (III) undergoes oxidation and cyclization to give the title compound analogue (IV).

The known 1,5‐epoxyperhydroazulenone (I) is treated with AlI3in acetonitrile (II) with the intention to cleave the ether bridge.

The benzopyran (VIII) is prepared by an efficient route starting from the pyranone (I) via (III), (IV) and (V).

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The betains (II) or (VI) undergo intramolecular cycloadditions to afford the tricyclic products (III) or (VII), respectively.

Substitution reaction of the nitrobenzenes (I) with the sodium phenoxides (II) or (IV) or sodium 1‐naphthoxide (VI) produces the diaryl ethers (III), (V), and (VII).

General methods for the preparation of a variety of the title compounds such as (V), (VII) or (IX) are described.

Methyl 3,5‐dihydroxybenzoate (I) undergoes twofold cyclization reaction with cyclohexanecarboxaldehyde (II) in the presence of an acid to give the heterocyclic bisspirocyclohexane (III).

Depending on the diacylamine (II) used, the title reaction leads either to N‐alkylated (III) or O‐alkylated products (IV).

The bicyclic alcohol (VIII) and the ketone (XII) are prepared from the bromide (I) via the common intermediate (VI).