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A novel (2,3)-sigmatropic rearrangement is proposed as a suitable method to synthesize N-hydroxyallylamines.

The reaction of 1,3,5-triazine with dinitrogen pentoxide quenched with methanol to produce 1,3,5-trinitro-2,4,6-trimethoxyhexahydrotriazinewas demonstrated. Two isomers, the cis- and trans-2,4,6-trimethoxy-1,3,5-trini-trohexahydrotriazine were isolated in about an equimolar ratio.

Research is presented concerning the asymmetric allylic alkylation reactions of nitromethane and 2-diarylphosphino-4,5-dihydrooxazole ligands in the presence of a Pd catalyst. The diastereoselectivity and enantiomeric excesses of the reaction are discussed.

Studies of catalytic enantioselective reactions of imines have aimed at establishing highly efficient processes for the synthesis of chiral nitrogen-containing compounds. However, several limitations have hindered the attainment of this goal. Carbon-carbon bond-forming reactions are handicapped by substrate limitations. Imines with alpha-protons have been found to be unstable and not conducive to efficient reactions. Researchers continue their experiments on establishing practical ways to obtain optically pure nitrogen-containing compounds.

The previous study showed that the activation parameters for the decomposition of O2NOO- were A = 1 X 10(super 12)/sec and Ea = 16.3 kcal/mol utilizing the pulse radiolysis method for generation of O2NOO-. These values were substantially smaller than A = 7.7 X 10(super 20)/SEC AND eA = 28.7 kcal/mol, which were computed by Regimbal and Mozurkewich by following the decomposition of O2NOOH as a function of pH at pH < 5.

The structures and stabilities of helionitronium trication N[O.sub.2][He.sup.3+] and helionitrosonium trication HeN[O.sup.3+] were calculated at the ab initio MP2/6-31G** level. The [C.sub.8] symmetry structure was found to be a minimum for the N[O.sub.2][He.sup.3+] trication, which is isoelectronic and isostructural with the previously studied N[O.sub.2][H.sup.2+]. Dissociation of the [C.sub.s] symmetry structure into N[O.sup.+] and O[He.sup.2+] is thermodynamically preferred by 183.1 kcal/mol (1 cal = 4.18 J), although a kinetic barrier of 12.4 kcal/mol has to be overcome. The [C.sub.[infinity]v] symmetry structure was also found to be a minimum for the HeN[O.sup.3+] trication.

The aqua complex derived from the DBFOX/Ph ligand and Ni(ClO4)2*6H2O serves as a superior chiral Lewis acid catalyst in the presence of MS 4A in the asymmetric 1,3-dipolar cycloadditions of nitrones to 3-(2-alkenoyl)-2-oxazolidinones. Enantioselectivities of up to >99% ee were noted, with minimum catalytic loading of 2 mol %. Such high selectivities are attributed to the presence of MS 4A. The transition structure involving a trigonal-bipyramid substrate complex results in such excellent diastereoselectivities and enantioselectivities for the 3,4-trans-isoxazolidines.

The first azo anion radical complexes of ruthenium were isolated in pure form. The relevant azo ligands and complexes were described and the reaction of 2-(arylazo)pyridines of type 1(6) with 2(7) was analyzed. It was found that ruthenium-hydrogen bond cleavage plays an important role in the formation of azo anion radicals. The isolation of azo anion radical complexes of ruthenium also provided an experimental measure of the azo anion radical nitrogen-nitrogen length.

The dimethyldioxirane (DMD) oxidation of sigmaH adducts produced from nitroarenes and the carbanion of 2-phenylpropionitrile was observed to surprisingly form phenols as the primary products while nitroarenes were produce in very small quantities, if any. Phenol production was increased when a little amount of water was added at the initial phase of the reaction. This unique oxidation of Meisenheimer complexes affords the first direct synthesis of phenols from nitroarenes.

A prototype for 2-pi-electron Huckel aromatic systems were prepared using cyclopropenium salts. Calculations indicate that the azirinyl cations (illustration B) show less obvious aromatic character because of the pi-polarization toward nitrogen. The ring strain could be reduced by replacement of the nitrogen atom by a phosphorus center. The synthesis and reactivity of a stable diphosphirenylium salt bound in an etasuper2-manner, to a transition metal center is reported.

The hydrothermal reaction of Ni(II) and the rodlike 4,4'-bipyridine ligand was observed to produce an extended 1-D noninterpenetrated open framework similar to a railroad with large pores of 11 x 11 angstroms aperture. This railroad 1-D motif is a unique member of metal-4,4'-bpy extended networks, where structures described in terms of the diamond and alpha-ThSi2 networks, as well as hexagonal and square grids, and ladder motifs have been produced and structurally analyzed.

The isostructural metalloporphyrin chalconitrosyl complexes Ru(TTP)(NE)Cl (E = O, S) are synthesized and characterized. A N-bound thiazate complex, Ru(TTP)(NO)(NSO), is formed instead of the expected halide methatheis when Ru(TTP)(NE)Cl is treated with silver nitrite. The thionitrosyl/nitrite to nitrosyl/thiazate transformation represents a remarkable case of an oxo transfer reaction and illustrates the propensity for the formation of ruthenium nitrosyl complexes.

The biggest structurally characterized rhodium cluster (Rh28N4(CO)41Hx)4- has been synthesized and investigated. The pattern of the Rh-Rh bond distances followed the overall idealized C3v symmetry and can be partitioned into 17 topologically independent classes. This massive cluster molecule which reproduces the ccp lattice of the bulk metal, with relatively small swelling due to several interstitial nitrogen atoms, indicates the possibility that a binary nitride of rhodium could exist.

Variable-temperature, dynamic 1H NMR was employed to examine ground- and excited-state proton transfers in the isolectronic nitrogen analog indigodiimine in a mixed solvent. The results, which proved the highly fluxional structure of the vinylogous N-arylamidine, confirmed its potential to adopt eight interconverting molecular states due to the combination of proton tautomerization and NH2 group rotation.

The reaction of chlorine with ammonium chloride (concentration 0.01-2.0M) in the presence of hydrochloric acid (pH 4.6 to 6.8) gives explosive nitrogen trichloride (NCl3) compound in a temperature range of 20 to 90 degree celsius. NCl3 is partially soluble in aqueous medium. The transition of NCl3 to gas-phase is initially low, but starts increasing once the solubility limit of NCl3 in solution exceeds 17 mmol/L. Precautions should be taken while handling amines and chlorine together to avoid dangerous conditions.

A nitrosobenzene dimer complex has been isolated as an intermediate in allylic aminations of PhNHOH and PhNO catalyzed by iron chlorides. The metal complex, which is the first of its kind to be structurally proven to have a C-nitroso dimer ligand, also appears to be the 'active aminating agent' in allylic aminations catalyzed by iron salts. This was concluded from its reactivity and regioselectivity in the allylic N-functionalization of olefins.

Mechanistic, chemical and spectroscopic observations of the photolysis of 4,4'-diazidostilbene are analyzed. Specifically, the primary and secondary products resulting from the ultraviolet/vis irradiation of the aromatic biazide at 77 K was compared with other substituted mononitrene precursors via a kinetic analysis. The biphotonic reactions culminated in the formation of a triplet mononitrene caused by two-fold hydrogen abstraction from the solvent.

The preparation and characterization of the novel imine (E)- and (Z)-1-H-difluoromethanimine are described. The synthesis involves the reaction of CF2=NF with triphenylphosphine and subsequent reaction with H2O to form the E-isomer. The isomerization to the Z-isomer has been catalyzed by acids. The products were characterized by NMR spectroscopy.

The synthesis and characterization of 2-alkyl-2-methyl-3-butenitriles are described. The scheme involves the Cope-type elimination reactions of 2-methyl-2-butenal N,N-dimethylhydrazones with magnesium monoperoxyphthalate at -5 degrees C. The target compounds were produced in good overall yield of 66%-85% The reaction conditions for the synthesis are presented.

Nickel(0)-catalyzed intramolecular (4 + 2) cycloadditions of nitrogen-containing dienynes have been evaluated as method for the synthesis of hydroisoindole and hydroisquinoline derivatives. The results showed that the reactions can tolerate amide, sulfonamide and carbamate functionalities. The method has been applied to the expedient synthesis of (+/-)-19.20-didehydroyohimbane, the pentacyclic framework of the medicinally active Rauwolfia alkaloids.

The synthesis and characterization of two novel nitridomanganese(V) salen-derived complex which can be used as reagents for the amination of electron-rich enol ethers are described. The complex can be activated for nitrogen transfer with trifluoroacetic acid. N-trifluoroacetyl alpha-amino ketone products were formed when the nitridomanganese(V) salen-derived complexes were activated in the presence of some silyl enol ethers.

The synthesis of 1-pyrroline derivatives from gamma-nitrocarbonyl compounds is presented. The synthesis involves the transition-metal complex-catalyzed N-heterocyclization of nitroarenes by carbon monoxide. The reaction was adapted to aliphatic nitro compounds by using a Ru3(CO)12/1,10-phenanthroline system.

The synthesis of deaza-thia analog 10-substituted 7,8-dimethylpyrimido(5,4-b)(1,4)benzothiazine(1H,3H)-dione is described. The synthesis is based on the S-N type Smiles rearrangement and subsequent cyclization reaction of 6-( 2-aminophenyl thio)5-bromouracils. The reaction conditions necessary for the synthesis are presented.

The synthesis of dihydropyrrole, pyrrole and indole products is described. The method is based on the tandem nucleophilic addition-vinylidene carbene sequence reaction of alkynyliodonium salts in combination with substituted nitrogen nucleophiles (tosylamide ion, possesses a beta C-H bond). The results showed that the method offers an efficient pathway for preparing structurally complex compounds bearing these ring systems.

The reaction of azides with benzyltriethylammonium tetrathiolmolybdate has been examined. The scheme offers a simple and efficient means of preparing the corresponding arylamines. Imine derivatives were also prepared when the sulfur transfer reagent has been reacted with alkyl azides. The reaction conditions for each synthesis are presented.

The nuclear magnetic resonance and x-ray diffraction characterization of a stable carbene, 1,3-dimesitylimidazolin-2-ylidene, is discussed. Specifically, 1,3-dimesitylimidazolinium chloride was reacted with potassium hydride to form a 72%-pure, stable carbene as a colorless, crystalline solid. Its stability shows that a stable diaminocarbene may be obtained even without a C4-C5 double bond in the imidazole ring.

A L-tartaric acid precusor nitrone was added to 4-(benzyloxy)butyl magnesium bromide in the presence of THF resulting in the formation of indolizidine alkaloid lentiginosine with an (alpha)(sub D) value of +2.8. The resulting compound is a novel alpha-glucosidase inhibitor having only two hydroxyl groups and is extracted from leaves of Astragalus lentiginosus.

Tert-butyl diphenylmethyl nitroxide (compound L) is the first new metal-complex forming member of the alpha-H containing nitroxide group of chemicals. Its coordination properties are in line with other fully alpha-substituted analogs, but it is very stable and the coordination center is more accessible than the other analogs. When compound L is reacted with with bis (1,1,1,5,5,5,-hexafluoro-2,4-pentanedionato) copper(II) hydrate, or Cu(hfac)2H2O, a stable mixed-ligand complex of Cu(hfac)2L is produced. The complex forms needle-like crystals and is diamagnetic at room temperature.

Synthetic 1-aryl-1,2-dibromo-2-nitropropanes react with 2-propanenitronate in DMSO to yield 2-bromo-2-nitropropane and 2, 3-dimethyl-2,3-dinitrobutane. GC analyzes the products while cyclic voltammetry examines the redox properties of these compounds. High exothermicity of the reaction favors the ionic pathway in the reaction mechanism.

Two nitronyl nitroxide derivatives with a tetrathiafulvalene or a p-benzoquinone group at the nodal carbon are prepared and converted into conductive ion-diradical salts. Two types of intramolecular exchanges occur in ion-radicals from an open-shell acceptor or donor. The intramolecular ferromagnetic interaction is applicable for the construction of molecular magnetic systems having charge-transfer interactions.

Laser flash photolysis is employed for the observation of 2-fluorenyl- and 4-biphenylylacetylnitrenium ions in aqueous solution. Kinetic stabilities of arylnitrenium ions have been demonstrated by direct measurements and are compared with those of carbenium ions. Reaction of nitrenium ions with carbon nucleophiles occurs at the external nitrogen. The 'Azide-clock' method is employed to study the lifetimes of nitrenium ions.

Photolysis induces the 5-habogenated derivatives to yield corresponding nitrenium ions as suggested by studies on nitrenium ions, which are short-lived, cationic intermediates with a divalent nitrogen atom. Time-resolved methods can be used to identify arylnitrenium ions that are photochemically produced.

The synthesis and chemical behavior of three bis(imido)-bridged and imido-oxo-bridged iridium complexes Cp*Ir(mu-X)(mu-NR)IrCp* are described. The complexes are prepared by exchange reactions of the triple-bonded Cp*Ir(N-t-Bu) or Cp*Ir(N-Ph) with water and aniline. Further studies show that the complexes serve as effective imido and oxygen group transfer agents. The phenyl derivative undergoes hydrogenolysis to yield free aniline and a dihydrido-bridged complex.

A unique Li-N2 dication is prepared by accident in the course of studies on binuclear zirconium phosphinidene dianions. Sequential addition of n-butyllithium and Cp2ZrCl2 to phenylphosphine in tetrahydrofuran yields a black solid which, upon X-ray and spectroscopic analysis, turns out to be a salt of the dimeric anion (Cp2Zr(mu-PPh)2)2- with the dication (((THF)3Li)2(mu-N2))2+. The complex salt is extremely sensitive to heat and air, liberating N2 gas when so exposed.

An unsuccessful attempt to reproduce a published procedure leads to a modified route towards 3-pyrroline. The reaction of cis-1,4-dichloro-2-butene with hexamethylenetetramine and subsequent hydrolysisof the chloroallyl ammonium salt proceed well. The cyclization step with potassium carbonate, however, fails. Further trials show that mixing the chloroallylamine hydrochloride with two equivalents of diazabicyclo(5.4.0)undec-7-ene, followed by heating, produces the pyrroline in 63-65% yield.

The amido, imido and nitrido derivatives of the low-valent tungsten specie Tp'(CO)2W, where Tp' = hydrotris(3, 5-dimethyl-1-pyrazolyl)borate and their corresponding facile interconversions are reported. Tp'(CO)2W(NH2), a metal complex with both the carbonyl and amido ligands, is generated from the treatment of a Tp'(CO)2WI solution with ammonia in CH2Cl2. This complex exhibits an ambiphilic character and reacts as either hydride or proton donor.

Sodium trimethylsilanethiolate reduces aromatic nitro compounds to their corresponding arylamines in 83-98% yields. The reactions are applicable to nitrobenzenes with different substituents in their ortho, meta and para positions as well as to aryl substrates with two substituents and to nitropyridines. The sodium thiosilane can efficiently remove the methyl group from aryl methyl ester but, from nitrobenzene, prefers reduction of nitro groups over O-demethylation. Reaction with nitropyridines is faster than with nitroarenes but gives lower yields.

A study was conducted to analyze the synthesis of nitrogen heterocycles using catalytic ring-closing metathesis of non-cyclic dienes. Although metathesis of diene-amines is difficult, the catalytic ring-closing transformation method has proved effective in the cyclization of dienes to form nitrogen heterocycles.

The complex 1,5-Ph4P2N4S2 reacted with Li(Et3BH) in tetrahydrofuran to generate the corresponding dianion. The dianion reacted with diiodomethane to yield the bicyclic compound Ph4P2N4S2CH2 which possesses a methylene group bridging the sulfur atoms of the P2N4S2 ring. Deprotonation of the bicyclic compound resulted in the carbanion Ph4P2N4S2CHLi which, when reacted with iodomethane, gave Ph4P2N4S2CH(CH3).

The synthesis and characterization of a novel class of hybrid, fused-ring cluster triazenethiaborane compounds. The compound (mu2(4,exo-9)-1-SiMe3-3-H-N3)-arachno-6-SB9H10 is prepared from the facile reaction of nido-6-SB9H11 with trimethylsilyl azide. A single-crystal X-ray study of the compound shows a structure with a cage framework similar to those of other 10-vertex, 26-skeletal-electron systems.

The article discusses research methods used to discover nitroethylene's unimolecular decomposition rate.

Homo- and heterodinuclear complexes having the N3M(mu2-SR)3MN3 core (M = Fe, Co, Ni) were synthesized and characterized. The novel amine-thiolate ligand was then used for the preparation of dinuclear complexes of Fe, Co and Ni. A comparison of the electrochemical properties of (Co(super III)Ni(super II)(H3))2+ and (Ni(super III)Ni(super II)(H3))2+ shows that the Ni(super III/II) redox potential in the dinuclear complexes are influenced by the oxidation state of the adjacent metal ion.

The rearrangement rates of a number of nitrogen-containing 2-aryl-3,3-dimethylmethylenecyclopropanes to the corresponding 2-arylisopropylidenecyclopropanes have been used to calculate sigma.values. The technique, a means of measuring the radical stabilizing capability of the substituent, has led to the classification of a number of 'good' radical stabilizers. A group of 'Super Stabilizers,' substituents that have extraordinarily large radical stabilizing effects, has also been identified.