One Nitrogen Atom

Systems containing Nitrogen as the only Heteroatom.—One Nitrogen Atom. The aza[14]annulene (28) has been synthesized by the photolysis of (29) in pentane at —70°C. Its aromatic character is demonstrated by the large difference in chemical shifts of the three inner and the ten outer protons of ca 9.5 p.p.m. Variable-temperature H n.m.r. moreover demonstrates that the ring is confor-mationally mobile, producing an equilibrium of two degenerate species. 

An improved one-step conversion of alicyclic ketones (30) into lactams (31 n = 3-10) involves the use of hydroxylamine-O-sulphonic acid and methanoic acid at reflux temperature. Treatment of 1-chloro-l-nitroso- and 1-chloro-l-nitro-cycloalkanes (32) with PhaP and then hydrolysis of the intermediate chloro-imine provides a new route to (31 n — 3-6, or 10).  

The photochemical behaviour of the keto-azirine (33) depends on the wavelength of the radiation. If A = 254 nm, in ether, the oxazolophane (34) is formed, but if A 300 nm an unprecedented rearrangement to the keto-ketenimine (35) occurs. 

Bicyclic Compounds with Nitrogen Atoms in a Five-membered Ring. One nitrogen atom. Pyrolysis of 2 (methoxycarbonyloxy)isoindoline (403) at 500 °C and 0.01 mmHg gives isoindole (404), which is stable at ca. 70 K but 

spectra have been used to assign configurations and conformations to cis- and t/-a j -l,2,3,4,4a,9a-hexahydrocarbazoles (409).  

More than one nitrogen atom. cw-Fused bicyclic pyrazolines (410) are the predominant products of heating the phenylhydrazones (411) in acetic acid. It is argued that this result shows preferential axial attack on cyclohexene double bonds. 

The preparation and reactions of some 7,7-diethylpyrazolo[l,2-a]pyrida-zine-6,8(7JT)dione derivatives (412) have been reported.  

In an investigation of the mechanism of certain biological oxidations, iViV -dimethyltryptamine and pyridine N-oxide were irradiated, producing 1,8-dimethyl-3a-hydroxy-2,3,3a,8a-tetrahydropyrrolo [2,3-/ ]indole (413). The postulated intermediate is the epoxy-compound (414). 

Alkoxyaziridines, structure, properties, formation from O-nitrenes 90KGS291. 

Aziridine-2-carboxylic acid, asymmetric derivatives of 87MI5. Aziridines, formation from nitrenes and unsaturated compounds 79ZVK485. 

Aziridines in the synthesis of azomethine ylides 89AHC(45)231. Aziridines in the synthesis of natural products 86AHC(39)I81. Azirines as intermediates in pyrrole formation 87KGS1299. 3-Amino-2-//-azirines, synthesis and properties 90KGS867. Ethynylaziridines 87MI6. 

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In spite of the diverse nature of alkaloid structures, two structural units, i.e. fused pyrrolidine and piperidine rings in different oxidation states, appear as rather common denominators. We therefore chose to give several examples for four types of synthetic reactions which have frequently been used in alkaloid total synthesis and which provide generally useful routes to polycyclic compounds with five- or six-membered rings containing one nitrogen atom. These are ... 

In 1877, Maly (45) discussing formula 34 applied to thiohydantoine found it unable to explain the basic properties of the compound. He preferred a structure in which the -CH2-CO- group would be bonded to only one nitrogen atom. Meyer (46) prepared a monophenyl thiohydantoin (m.p. 178°C) by condensing diloroacetanilide with thiourea and proposed 42 for its structure. 

There are some reports on reactions involving complete N—N cleavage in diazirine reactions such as formation of amidine (205) from chlorophenyldiazirine, or on formation of products containing only one nitrogen atom. Betaine (206) was described as a product from difluorodiazirine and triphenylphosphine. Compound (207) is formed from decomposing (204) and cyclohexane (79AHC(24)63). 

Part 2 (Volumes 2 and 3) deals with mono- and poly-cyclic compounds with one or more six-membered heterocyclic ring, with nitrogen, oxygen and sulfur as the heteroatoms. Volume 2 contains the six-membered rings with one nitrogen atom (Part 2A) and Volume... 

On hydrogenation at 80°, or on electrolytic reduction, aphyllidine is converted into d-sparteine (p. 133). On exhaustive methylation one nitrogen atom is eliminated in three stages, leaving a product, b.p. 235-255°/ll mm., as a viscous, yellow, alkaline oil of uncertain composition. Aphylline, on similar treatment, yields hemiaphylline, CjgH jON, b.p. 217-220°, as a viscous, yellow oil, not markedly basic. 

Oxazine, metoxazine (or mazoxin), consists of a ring of four carbon atoms, one oxygen, and one nitrogen atom the two hetero atoms are in the 1,3-positions or meta ... 

Fused Heterocyclo-Quinolines Containing One Nitrogen Atom at Ring Junction Part 1. Four and Five Membered Heterocyclo-Quinolines... 

This chapter includes the recent various aspects of four and five membered heterocyclo-quinolines containing one nitrogen atom at the ring junction. They were subdivided according to the number of heteroatoms in the heterocyclic rings. The literature indicates that many of these heterocycles are of potential therapeutic value which leads to intensive research in the topic. On the other hand, there are various classes of heterocycles that fit under this heading but unreported yet. Consequently, efforts towards the synthesis of such unreported classes can be fruitful area of research. 

Pyrimidinopyrazines related to folic acid have been investigated in some detail for their antimeta-bolic and antineoplastic activities. A related compound, which lacks one nitrogen atom, has been described as an antiproliferative agent, indicating it too has an effect on cell replication. Aldol condensation of the benzaldehyde 99 with ethyl acetoacetate gives the cinnamate 100. This is then reduced catalytically to the acetoacetate 101. Reaction of that keto ester with 2,4,6- triami-nopyrimidine gives the product 102 which is subsequently chlorinated (103) and subjected to hydrogenolysls. There is thus formed piritrexim (104) [17]. 

Heterocycle (Sections 15.5, 24.9) A cyclic molecule w hose ring contains more than one kind of atom. l or example, pyridine is a heterocycle that contains five carbon atoms and one nitrogen atom in its ring. 

A molecule of ethylamine is made up of two carbon atoms, seven hydrogen atoms, and one nitrogen atom. 

The unknown gave a molecular ion at m/z 193 with fragment ions at m/zs 174, 148, and 42. From the abundance of the molecular ion, it is probably aromatic, and according to the Nitrogen Rule, contains at least one nitrogen atom. From accurate mass measurement data and an examination of the isotopic abundances in the molecular ion region, the molecular formula was found to be CnH15N02. 

Griess (1860) coined the prefix diazo for the nitrosation product of an aromatic amine, because he assumed that two nitrogen atoms replaced two hydrogen atoms of the parent aromatic compound. On the other hand, azobenzene received its name on the basis of the C H N ratio 6 5 1, indicating the replacement of one hydrogen by one nitrogen atom. 

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