Diaza-Compounds

Nitrogen Systems. - Monoaza- and Diaza-Compounds. Indolizine (555) dimerizes to 3,3 -bi-indolizine on heating with palladium in xyleneThe reaction of 2-methylindolizine with tropone yields a mixture of compound (556) and its 3, 4 -dihydro-derivative.  

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The 1,4-diaza compound 100, however, behaves quite differently and yields the salt 102 as the only isolatable product. The question of the presence or absence of the alternative salt (101) cannot be settled as easily as in the case of the 1,7-diazaindene 97 because 101 would not... 

The methods outlined, of course, are readily applicable to a wide variety of substituted heterocycles like the carboxyl, hydroxy and mercapto derivatives of pyridines, pyridine 1-oxides, pyrroles, etc. The application to amines and to diaza compounds such as pyrimidine, where the two centers are basic, is obvious except that now 23 takes the role of the neutral compound, 21 and 22 the roles of the tautomeric first conjugate bases, and 20 the role of the second conjugate base. Extensions to molecules with more than two acidic or basic centers, such as aminonicotinic acid, pyrimidinecarboxylic acids, etc., are obvious although they tend to become algebraically cumbersome, involving (for three centers) three measurable Kg s, four Ay s, and fifteen ideal dissociation constants (A ), a total of twenty-two constants of which seven are independent. 

Diaza compound 669 condensed with bromobutyryl chloride under classical basic conditions gives bicyclic derivative 670. This compound can be further functionalized, for example, via classical enolate chemistry (Scheme 110)... 

Transition-metal Catalyzed Decomposition of Aliphatic Diaza Compounds... 

A variation on the usual synthesis of pyrazines, reaction of 1,2-diones with diamines, was the use of the diazabutadiene 81 in place of the dione <06JOC5897>. In another paper, the same diaza compound 81 reacted with sarcosine methyl ester, in a complex set of reactions, to produce quite good yields of 5-oxy-pyrazine-2-carboxamides 82. The A-methyl was lost and direct aromatisation occurred, presumably, due to cleavage oftheN-N bond <06SL2403>. 

Many reactions that proceed with elimination of a gas (N2, COz, etc.) and formation of radical-pair intermediates show considerable stereochemical differences in solution and in the crystal. Thus, solid-state photolysis of the diaza compound 176 yields, among other products, cis-1,2-diphenylcyclopentane, 177 no trans isomer, 178, has been detected. Irradiation of 176 in solution leads to mixtures in which the trans product 178 predominates (244). 

In contrast, the radical cation of the tetracychc system is significantly distorted The parent system has D2d symmetry and a b2 HOMO, whereas the radical cation is distorted toward 2 equiv structures of Cav symmetry ( E), with a two-center three-electron N-N bond (3 +). The ESR data (an = 0.709 mT, 4N ah = 0.768 mT, 8H, N—C—N ah = 0.414 mT, 8H, N—C—support the rapid interconversion of the two structures. The structure of 3 " is one of many doubly or multiply bridged diaza compounds forming three-electron N—N bonds (e.g., 4 " ). Many additional examples involving three-electron S—S or I I bonds are also known. Dioxetane radical cations (e.g., 5 ), characterized by ESR spectroscopy as intermediates in oxygenations (cf.. Section 5), contain analogous three-electron 0—0 bonds. 

Reactions of cis diaza compounds with carbonyl compounds 904... 

An interesting ring-contraction route to a 1,4-diazocine was reported by Koch and Dessy, who electrochemically reduced the 12-membered cyclic diaza compound 59 and obtained a phenanthrodibenzodiazocine 60 as a minor product (the major product being an azepinodiazepine) (82JOC4452). 

The pure compound 4a is used for further reactions. In order to obtain solid or crystalline products, the 1,3-diaza-compound can be transferred into the mono-quartemary ammonium- salt 5a [5]. (Eq. 4) by using Mel as methylating agent. 

Major nitrogen compounds in petroleum crude oil have been characterized mainly into four classes pyridines, diaza compounds, carbazoles, and amides... 

There are significantly fewer data available on the conformational behavior of 3-oxa-7-azabicyclo[3.3.1]nonanes than for the 3,7-diaza compounds described above. 

To investigate whether the radical cations of the diazadithiafulvalenes would undergo eoupling with carbon radicals at a different rate than TTF+, eomparative experiments were performed with the allyl sulfide 99. This led to the products 100 and 101 as for TTF (Scheme 16). However the yield of the bicyclic produet was higher for the diaza compounds, indicating a slow-down in the kinetics of the recombination reaction. Although this is likely to be a fairly small change, it is clear that the modulation of kinetics in this way may be useful with radical-polar crossover reaetions to permit slower cyclizations to occur before recombination. 

Diaza-Compounds. The nitrone (514) reacts with phenylmagnesium bromide to give... 

Monoaza-Compounds 273 Diaza-Compounds 273 Triaza-Compounds 273... 

Monoaza-Compounds 276 Diaza-Compounds 276 Triaza-Compounds 276 Tetra-aza-Compounds 279 Mixed Oxygen-Nitrogen Systems 279... 

Diaza-compounds. The pyrrolo-pyrazole derivative (705) is one of the products of the action of acids on the tosylhydrazone H2C=CMe(CH2)2CH=N—NHTos. The reaction of 2,5,5-trimethyl-l-pyr-roline iV-oxide (706) with the ketenimine Ph2C=C=NPh yields the pyrrolo-imidazole (707)/ Pyrazolidin-3-one and 3-chloropropanoyl chloride combine to form the dioxopyrazolopyrazole (708)/ Irradiation of l-(o-iodoben-zoyl)imidazole (709 R=H) produces the indolobenzimidazolinone (710) the... 

Diaza-compounds. Phenacyl bromide reacts with 2-aminopyridine 1-oxide to yield 2-phenylimidazo[l,2-a]pyridin-3-ol (769) another derivative of this ring system, compound (771), is produced by the action of diphenylketen on the sulphilimide (770), dimethyl sulphide being eliminated.(6-Methyl-2-pyri-dyl)acetyl azide (772) forms the dihydroimidazo[3,4-a]pyridinone (773) on heating." Whereas l-methylpyrrole-2-aldehyde and other heterocyclic aldehydes react with tosylmethyl isocyanide to give oxazoles, e.g. (774), pyrrole-2-aldehyde affords the 6-azaindolizine (775). The action of potassium amide on the derivative (776) of 3-bromopyridine furnishes the pyrrolo[3,4-c]pyridine (777) by cyclization of an intermediate pyridyne." ... 

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