Novel Type Of Reaction Research Articles

New Type of Reaction of Lanthanide Hydrido Complexes with C60: Oxidative Dehydrogenation vs Addition. The Reversible σ-C60−C60 Bond Formation in Complex [{(Me3Si)2NC(NCy)2}2Lu(Et2O)+](C60−•)

A novel type of reaction of lanthanide hydrido complexes with C60 is described. The hydride anion of complex [{(Me3Si)2NC(NCy)2}2Lu(μ-H)]2 reduces C60 (1:2 molar ratio, toluene, 20 °C) to the radical anion, and the reaction results in the formation of ionic complex [{(Me3Si)2NC(NCy)2}2Lu(Et2O)+](C60−•). At low temperature (below ∼120 K) reversible dimerization of radical anions C60−• occurs and affords the complex [{(Me3Si)2NC(NCy)2}2Lu(Et2O)+]2[(C60−)2]·2(C7H8)·(Et2O) with the diamagnetic σ-bonded (C60−)2 dianion.

Direct Identification of a Bacterial Manganese(II) Oxidase, the Multicopper Oxidase MnxG, from Spores of Several Different Marine Bacillus Species

Microorganisms catalyze the formation of naturally occurring Mn oxides, but little is known about the biochemical mechanisms of this important biogeochemical process. We used tandem mass spectrometry to directly analyze the Mn(II)-oxidizing enzyme from marine Bacillus spores, identified as an Mn oxide band with an in-gel activity assay. Nine distinct peptides recovered from the Mn oxide band of two Bacillus species were unique to the multicopper oxidase MnxG, and one peptide was from the small hydrophobic protein MnxF. No other proteins were detected in the Mn oxide band, indicating that MnxG (or a MnxF/G complex) directly catalyzes biogenic Mn oxide formation. The Mn(II) oxidase was partially purified and found to be resistant to many proteases and active even at high concentrations of sodium dodecyl sulfate. Comparative analysis of the genes involved in Mn(II) oxidation from three diverse Bacillus species revealed a complement of conserved Cu-binding regions not present in well-characterized multicopper oxidases. Our results provide the first direct identification of a bacterial enzyme that catalyzes Mn(II) oxidation and suggest that MnxG catalyzes two sequential one-electron oxidations from Mn(II) to Mn(III) and from Mn(III) to Mn(IV), a novel type of reaction for a multicopper oxidase.

ChemInform Abstract: Formation of 1,2‐Oxazine Derivatives: A Novel Type of Reaction Between 2‐Aminooxazoles and Maleic Acid Imide.

AbstractChemInform 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.

Formation of 1,2-oxazine derivatives: A novel type of reaction between 2-aminooxazoles and maleic acid imide

N,N-Disubstituted 2-aminooxazoles in acetic acid at 20°C undergo addition of maleinimide, converting to alkylidene succinimides or 1,2-oxazine derivatives.

Synthesis of a Bis(silanolate) Complex from a Bis(silyl) Complex by Air Oxidation: Evidence for the Participation of Silanolate Complexes in the Transition-Metal-Catalyzed Formation of Disiloxanes from Hydridosilanes

In a novel type of reaction, the bis(silyl) complex (κ2-P,N)-(PN)Pt[o-(Me2Si)2C6H4] (PN = 2-(diphenylphosphino)-N,N-dimethylaniline) was quantitatively converted to the bis(silanolate) analogue (κ2-P,N)-(PN)Pt[o-(OMe2Si)2C6H4]. Reaction of the bis(silanolate) complex with 1,2-bis(dimethylsilyl)benzene under argon leads to the starting bis(silyl) complex along with 1,1,3,3-tetramethyl-4,5-benzo-2-oxa-1,3-disilacyclopent-4-ene. In air the bis(silane) is quantitatively converted to the siloxane by catalytic amounts of the bis(silanolate) complex.

Self-processing 2A-polyproteins--a system for co-ordinate expression of multiple proteins in transgenic plants.

Achieving co-ordinate, high-level and stable expression of multiple transgenes in plants is currently difficult. Expression levels are notoriously variable and influenced by factors that act independently on transgenes at different genetic loci. Instability of expression due to loss, re-arrangement or silencing of transgenes may occur, and is exacerbated by increasing numbers of transgenic loci and repeated use of homologous sequences. Even linking two or more genes within a T-DNA does not necessarily result in co-ordinate expression. Linking proteins in a single open reading frame--a polyprotein--is a strategy for co-ordinate expression used by many viruses. After translation, polyproteins are processed into constituent polypeptides, usually by proteinases encoded within the polyprotein itself. However, in foot-and-mouth disease virus (FMDV), a sequence (2A) of just 16-20 amino acids appears to have the unique capability to mediate cleavage at its own C-terminus by an apparently enzyme-independent, novel type of reaction. This sequence can also mediate cleavage in a heterologous protein context in a range of eukaryotic expression systems. We have constructed a plasmid in which the 2A sequence is inserted between the reporter genes chloramphenicol acetyltransferase (CAT) and beta-glucuronidase (GUS), maintaining a single open reading frame. Here we report that expression of this construct in wheatgerm lysate and transgenic plants results in efficient cleavage of the polyprotein and co-ordinate expression of active CAT and GUS. Self-processing polyproteins using the FMDV 2A sequence could therefore provide a system for ensuring co-ordinated, stable expression of multiple introduced proteins in plant cells.

A novel type of reaction in the chemistry of graphite intercalation compounds. The preparation of alkali metal graphite intercalation compounds by ion exchange reactions

The treatment of KC 8 or KC 24 with a solution of LiCl or LiClO 4 in tetrahydrofuran (THF) results in the exchange of K +ions in the GIC for Li + ions. Depending on the ratio salt/GIC, ternary Li-THF-GICs with either d i = 12.5 A ̊ or d i = 7.16 A ̊ 5 have been obtained. Analogous reactions between KC 8 or KC 24 and solutions of NaI in THF lead to the formation of Na-THF-GIC with d i = 11.2 A ̊ . The same GIC was prepared by reactions of LiC 6 or LiC 12 and solutions of NaI in THF. Li-THF-GIC can be also obtained by reacting Na(NH 3) x C 14 with solutions of LiCl in THF. A model to explain the mechanism of ion exchange of intercalated alkali metal ions with ions in THF solution is proposed.

Ring–chain rearrangements of phosphirane

Ab initio molecular orbital calculations have been used to explore the C2H5P potential-energy surface. Geometries were optimized at the MP2/6-31G(d,p) level while relative energies were estimated using QCISD(T)/6-311 G(d,p) calculations and corrected for zero-point energies. Among C2H5P isomers, phosphirane 1, vinylphosphine, 2, 1-phosphapropene, 3, and 2-phosphapropene, 9, are low-energy isomers and have similar energy content. 1 lies only 5 kJ mol–1 above the most stable isomer, 9. This is in line with the experimentally observed equilibrium between substituted phosphiranes and vinylphosphines. The 1–2 rearrangement is a single-step process with an energy barrier of 235 kJ mol–1, which is not inconsistent with experimental thermal reactions at 500 °C. The 1–3 interconversion seems possible via ethylphosphinidene, 5, but 5 is not an equilibrium structure. The 2–3 isomerization is possible via either an antarafacial or a suprafacial 1,3-hydrogen shift with a barrier height of ca. 263 kJ mol–1. This represents the first example of an accessible suprafacial 1,3-hydrogen shift. The 1,3-hydrogen shift in 2-phosphapropene remains an antarafacial mode with an energy barrier of 288 kJ mol–1(in comparison with 345 kJ mol–1 in propene). Phosphinoethylidene, 4, is a high-energy isomer lying 201 kJ mol–1 above 1 and separated from 2 and 3 by moderate energy barriers (61 and 58 kJ mol–1). 4 is not involved in interconversions of 1, 2 and 3. While 1, 2-H2 loss from 3 giving CH3—CP or CH2CPH is unlikely, cycloreversion of 1 giving an alkene plus a phosphinidene is a realistic thermal process and thereby a possible mechanism for the formation of CH3—CP upon thermolysis of vinylphosphirane at 700 °C. Conversion of phosphirane to 9 is possible by two distinct two-step pathways: the first involves (methylphosphino) methylene, 8, as an intermediate whereas the second pathway involves bis(methylene)phosphorane, 10. The latter is favoured over the former. Overall, these ring–chain isomerizations of phosphirane constitute a novel type of reaction of phosphorus compounds which do not exist in either carbon or nitrogen analogues.

The photo-Nazarov cyclization of 1-cyclohexenyl phenyl ketone revisited. Observation of intermediates

The photochemical transformation of 1-cyclohexenyl phenyl ketone ( 1) to the hexahydrofluorenone 2 (“photo-Nazarov cyclization”) was reinvestigated on the level of conventional preparative chemistry backed up by nuclear magnetic resonance (NMR) spectroscopy and deuteration experiments. Hitherto unreported intermediates were detected. These include the enol 8 and, in non-protic media, the crystalline dimers 3 and 4. Dimer 3, which was characterized by single-crystal X-ray analysis, is a kinetically stable non-conjugated enol which readily isomerizes to 4 on acid-base catalysis. Dimer 4 is photolysed to give ultimately 2. The enol 8 is sufficiently long-lived to be seen in the 1H NMR spectra of freshly irradiated solutions of 1 in CD 3OD and of 4 in CD 3OD or CD 3CN before it isomerizes to 2. Enol 3 resuls from trapping of the oxyallyl 7, the presumed precursor of the enol 8, by 8 in a novel type of reaction. Irradiation of 1 in the presence of 1,3-cyclopentadiene (CPD) gives adducts 10–16. Adducts 13–16 appear to be derived from 7, whereas 10, 11 and 12 possess the structures of Diels-Alder adducts of CPD to the trans-cyclohexene isomer of 1 ( 6). The intermediacy of 6 as the primary photoproduct is also suggested by futher circumstantial evidence.

Transition metal complexes with sulphur ligands. Part 67. A novel type of reaction: nucleophilic alkylation of thiolato ligands by carbanions via intramolecular electron transfer. Alkylation and reduction of [W(S2C6H4)3] by lithium alkyls

The reaction of [W(S2C6H4)3]1 with LiMe depends on the concentration of the latter and yields either the anionic tungsten(IV) complex [NR4][W(S2C6H4)2(MeSC6H4S)](R = Me, 2a; or Et, 2b) or the anionic tungsten(V) complex [NMe4][W(S2C6H4)3]3b. This novel type of reaction demonstrates the reactive versatility of transition-metal sulphur centres and is of importance for the understanding of trans-methylation reactions catalysed by oxidoreductases with sulphur-co-ordinated transition-metal centres, e.g. CO dehydrogenase. When 1 is treated with LiEt, LiCH2But or LiPh only a reduction of 1 takes place yielding 3b. The reaction of complex 1 with 2 equivalents of LiBun affords the dianionic tungsten(IV) complex [NMe4]2[W(S2C6H4)3]4. The electrophilic alkylation of 4 by 2 equivalents of R3OBF4(RMe or Et) or of 2b by 1 equivalent of Me3OBF4 leads to the doubly alkylated complexes [W(S2C6H4)(RSC6H4S)2](R = Me, 5a; or Et, 5b).

ChemInform Abstract: Oligomethylenation of Bicyclopropylidene by Diazomethane in the Presence of Palladium(II) Acetate.

AbstractIn the presence of Pd(OAc)2 the reaction between bicyclopropylidene (I) and diazomethane (II) yields the expected dispiroheptane (III) as the main product along with the hydrocarbons (IV)‐(XIII), which are the products of oligomethylenation, a novel type of reaction.

ChemInform Abstract: Substitution of Allylic Hydrogen by an External Nucleophile ‐ A Novel Type of Reaction of Alkenes with Sulfenyl Chlorides.

AbstractIn the presence of LiClO4 the concerted reaction between the alkenes (I), the arylsulfenyl chlorides (II) and dimethyl sulfide (III) yields the sulfonium salts (IV).

Reductive dechlorination of 2,4-dichlorobenzoate to 4-chlorobenzoate and hydrolytic dehalogenation of 4-chloro-, 4-bromo-, and 4-iodobenzoate by Alcaligenes denitrificans NTB-1.

Alcaligenes denitrificans NTB-1, previously isolated on 4-chlorobenzoate, also utilized 4-bromo-, 4-iodo-, and 2,4-dichlorobenzoate but not 4-fluorobenzoate as a sole carbon and energy source. During growth, stoichiometric amounts of halide were released. Experiments with whole cells and cell extracts revealed that 4-bromo- and 4-iodobenzoate were metabolized like 4-chlorobenzoate, involving an initial hydrolytic dehalogenation yielding 4-hydroxybenzoate, which in turn was hydroxylated to 3,4-dihydroxybenzoate. The initial step in the metabolism of 2,4-dichlorobenzoate was catalyzed by a novel type of reaction for aerobic organisms, involving inducible reductive dechlorination to 4-chlorobenzoate. Under conditions of low and controlled oxygen concentrations, A. denitrificans NTB-1 converted all 4-halobenzoates and 2,4-dichlorobenzoate almost quantitatively to 4-hydroxybenzoate.

ChemInform Abstract: Stepwise Addition of MeS+ to a Metal‐Carbon Triple Bond ‐ A Novel Type of Reaction in the Chemistry of Carbyne Complexes.

AbstractSuccessive electrophilic attack on a carbyne and a carbene C atom characterizes the title reaction, in which first the cationic complex (III) and then the doubly positive‐charged complex (IV) is formed from the carbyne‐W complex (I).

Radical Switch Reaction. A Novel Reaction between Two Free Radicals in a Solvent Cage

Abstract Studies on the thermal decomposition of t-butyl phenylazo sulfone suggested the occurrence of a radical switch reaction, a novel type of reaction between two radicals. A primary geminate radical pair, t-butanesulfonyl and phenyl radical pair, exchange sulfur dioxide to form a new radical pair consisting of t-butyl and benzenesulfonyl radicals. The generation of benzenesulfonyl radical was confirmed by its ESR spectrum and the isolation of products containing a benzenesulfonyl group.

Aminierende, reduktive Kupplung aromatischer Aldehyde mit Tris(dialkylamino)methylvanandium (IV) zu N,N,N′,N′‐Tetraaalkyl‐1,2‐diaryläthylendiaminen

AbstractAminative Reductive Coupling of Aromatic Aldehydes to N,N,N′,N′‐Tetraalkyl‐1,2‐diarylethylenediamines, Induced by Tris(dialkylamino)methylvanadium (IV)In a novel type of reaction, certain aromatic aldehydes (benzaldehyde, p‐methoxybenzaldehyde, 1‐naphthaldehyde, furan‐2‐carbaldehyde) and secondary amines are coupled to give N,N,N′,N′‐tetraalkyl‐1,2‐diarylethylenediamines 1–6. The reagents are tris(dialkylamino)methylvanadium(IV) compounds (cf. Eqn. 2). These are generated in situ either from isolable chlorotris(dialkylamino) vanadium(IV) (Eqn. 3), or preferably, from an Et2O/pentane solution of VCl4 which is treated sequentially with 3 equiv. of lithium dialkylamide, 1 equiv. of MeLi, and 0.8 equiv. of an aromatic aldehyde, to give the products 1–6 in a one‐pot preparation (Scheme 2). The yields range from 14 to 54%. The diastereoisomeric mixtures (meso‐ and (±)‐forms) obtained are separated by chromatography (Al2O3, petroleum ether/Et2O/Et3N), and the pure stereoisomers fully characterized. A mechanism of the reductive coupling induced by CH3V (NR2)3 is proposed (Scheme 1).

ChemInform Abstract: REACTIONS OF TRICYCLIC VINYLCYCLOPROPANES WITH METAL CARBONYLS

AbstractBestrahlung der Verbindung (I) in Gegenwart von F e‐pentacarbonyl liefert die Komplexe (II) und (III), die in die Verbindungen (IV) bzw. (V) übergeführt werden.

Reactions of Tricyclic Vinylcyclopropanes with Metal Carbonyls

AbstractIrradiation of the tricyclic vinylcyclopropane 3 and Fe(CO)5 resulted in the formation of the s̀,π‐bonded iron complex 7 and the π,π‐bonded iron complex 8 (Scheme 2). Complex 8 was easily degraded with silica gel to give hydrocarbon 9, which reproduced 8 by photolysis in the presence of Fe(CO)5. Photolysis of 7 afforded a mixture of 3 (23%), 9 (27,5%), and three other hydrocarbons. Oxidative degradation of 7 with ceric ammonium nitrate in methanol gave the dimethoxy‐hydrocarbon 10. ‐ The tricyclic hydrocarbon 3 isomerized thermally to the bicyclic hydrocarbon 11 (with CH3C(9) in an exo position) via a homosigmatropic [1,5]‐H‐shift. On the other hand, 3 was converted into the other isomer 14 (with CH3C(9) in an endo position) by action of Mo(CO)6 or TsOH. Both isomers 11 and 14 reacted with 4‐phenyl‐1,2,4‐triazoline‐3,5‐dione to give the isomeric Diels‐Alder adducts 12 and 15, respectively, which were photochemically converted into the cage compounds 13 and 16, respectively (Scheme 3). ‐ Photochemical reaction of the tricyclic vinylcyclopropane 6 with Fe(CO)5 gave the σ,π‐bonded iron complexes 17 and 18. Heating of 17 at 80° resulted in a loss of one mol of carbon monoxide to give 18 in quantitative yield. Oxidative degradation of 17 with ceric ammonium nitrate in ethanol afforded the polycyclic lactones 19 and 20 by a novel type of reaction (Scheme 4). ‐ The tricyclic ketone 21 was thermally converted into the α,β‐unsaturated ketone 22 via a homosigmatropic [1,5]‐H‐shift. The configuration at C(7) of 22 was confirmed to be same as that of 11 (CH3C(9) in an exo position) by chemical conversions: 22 was reduced with NaBH4 to alcohol 23 which, in turn, was dehydrated with POCl3/pyridine to 11 (Scheme 5). Reaction of ketone 21 with Mo(CO)6 gave the α,β‐unsaturated ketone 25 and a cage compound X, whose structure was not fully elucidated. ‐ Reaction of the polycyclic epoxide 26 with Fe2(CO)9 or Mo(CO)6 yielded the allyl alcohol 27 in a novel type of reaction. The epoxides 29 and 32 were similarly converted into the corresponding allyl alcohols 30 and 33, respectively (Scheme 6).

Reaction of hexamethylditin with dicobalt octacarbonyl : A new cobalt-catalyzed disproportionation of hexamethylditin into tetramethyltin and dimethylstannylene

Hexamethylditin is known to react with dicobalt octacarbonyl in diethyl ether or pentane solution to give trimethyltincobalt tetracarbonyl as the sole product. As reported below in stronger coordinating solvents like THF the reaction is accompanied by a novel type of reaction, viz. a rapid dicobalt octacarbonyl-catalyzed disproportionation of hexamethylditin to give tetramethyltin and dimethylstannylene.

Isolation of purine oligonucleotides after hydrazinolysis of deoxyribonucleic acid

AbstractA modified version of the classical degradation of deoxyribonucleic acid by hydrazine has been used to obtain undamaged purine‐deoxyribo oligonucleotides. This method exploits hydraziniumchloride as a reagent capable of β‐elimination of the phosphate ester group from C(3) of a deoxyribose originally carrying a pyrimidine. Alkaline hydrolysis completes the required scission of the sugar‐phosphate backbone and removes remnants of the pyrimidine skeleton still attached to some deoxyribose residues. A novel type of reaction of alkaline phosphatase from E. coli was used with advantage to free the purine‐isostychs from substitution products of deoxyribose originally carrying a pyrimidine. The resulting purine‐isostychs have been separated and characterized.