NITROGEN CONTAINING HETEROAROMATICS

Lopes PEM, Lamoureux G, MacKerell AD, Polarizable Empirical Force Field for Nitrogen-containing Heteroaromatic Compounds Based on the Classical Drude Oscillator. Accepted for publication on J Comput Chem... 

PAEs with Nitrogen-Containing Heteroaromatic Rings. 192... 

Table 2 PAEs with nitrogen-containing heteroaromatic rings... 

Nitrogen-containing heteroaromatic compounds react with (chloromethyl)[(tri-methylsilyl)methyl] sulfide in the presence of CsF to afford fused 1,3-thiazolidines of type 130. These compounds are the result of a formal [3 + 2] cycloaddition of the parent thiocarbonyl ylide la across the C=N bond (170). In these cases, the formation of the five-membered cycloadduct is believed to occur in two steps via an intermediate onium ion. 

Covalent Hydration in Nitrogen-Containing Heteroaromatic Compounds I, Qualitative Aspects A. Albert and W. L. F. Armarego, Adv. Heterocycl. Chem., 1964, 4, 1-42. Covalent Hydration in Nitrogen Heteroaromatic Compounds II, Quantitative Aspects D. D. Perrin, Adv. Heterocycl. Chem., 1964, 4, 43-73. 

Electrophilic Substitution in the Series of Six-Membered Nitrogen-containing Heteroaromatic Compounds and Their N-Oxides Zh. I. Aksel rod and V. M. Berezovskii, Russ. Chem. Rev. (Engl. Transl.), 1970, 39, 627-643. 

Several types of nitrogen-containing heteroaromatic compounds are also capable of producing carboxonium-centered dications (Table 3).45 Among the dications 108-113, all have been shown to react with weak nucleophiles such as benzene, deactivated arenes, and even saturated hydrocarbons. Moreover, their reactivities greatly exceed that of comparable monocationic electrophiles. In the case of dication 111, for example, it is shown that it will condense with benzene in a hydroxyalkylative conversion (eq 36).45d... 

Albert, A., Armarego, W. L. F., Covalent Hydration in Nitrogen-Containing Heteroaromatic Compounds. I. Qualitative Aspects, 4, 1. 

Covalent Hydration in Nitrogen-Containing Heteroaromatic Compounds I. Qualitative Aspects... 

Pavlik, J.W. (2004) Photoisomerization of some nitrogen-containing heteroaromatic compounds, in CRC Handbook of Photochemistry and Photobiology, 2nd edn (eds W.M. Horspool and F. Lend), CRC Press, Boca Raton, FI, pp. 97-1-97-22. 

The lowest ionization potential of pyrazine and related nitrogen-containing heteroaromatic compounds has been measured. The experimental value of 9.29 eV is very similar to that of benzene (9.25 eV) and pyrimidine (9.35 eV) and is thought to be due to ionization from the highest occupied 77- orbital. Subsequent calculations have supported this assignment.04,65 (For a discussion of the relative ordering of 7r, a, and n orbitals, see Turner et ol.65a)... 

Bromoisoquinoline did not react with MeS ions in liquid ammonia, but 80% yield of the substitution product 4-isoquinolyl methyl sulphide was formed in the presence of amide ions. Isoquinoline and many other nitrogen-containing heteroaromatic compounds are known to react with amide ions to give anionic adducts 242289, which have been proposed to initiate the S l reaction by an ET to the substrate, which leads to the hetaryl radical. The radical couples only with MeS" ions 29°. 

The second generation are characterized by nitrogen-containing heteroaromatic ring-systems (Fig. 4.8). 

Stanovnik B (1991) 1,3-dipolar cycloadditions of diazoalkanes to some nitrogen containing heteroaromatic systems. Tetrahedron 47 2925-2945... 

Thus, radical addition reactions provide a useful means of functionalising pyridines, quinolines and isoquinolines, particularly when it is reasonable to employ the heteroaromatic base in excess. Intramolecular variants of the reaction are devoid of that limitation and have been widely exploited in the synthesis of nitrogen-containing heteroaromatics. The mildness of the reaction conditions have found favour in natural products total synthesis and medicinal chemistry programs. These bare testament to the reactions worth and have raised its stature from academic curiosity to useful synthetic tool. 

So far, valence bond isomers of oxygen-, sulfur- and nitrogen-containing heteroaromatic compounds were discussed where no benzvalene-type isomers had been isolated. The authors of this article synthesized tetrakis(trifluoromethyl)-l,4-diphos-phabenzene m> and obtained a diphosphabenzvalene by the photoreaction 172). The trifluoromethyl groups stabilize diphosphabenzene which is an electronically unstable compound (157). Thus, tetrakis(trifluoromethyl)-1,4-diphosphabenzene can be isolated. 

---