Chemistry of unsaturated nitrogen heterocyclic

The Chemistry of Unsaturated Nitrogen-Heterocyclic Compounds Containing Carbonyl Groups... 

Stanovnik and co-workers (100,101) systematically investigated the cycloaddition reactions of diazoalkanes with unsaturated nitrogen heterocycles, such as azolo-[l,5-fl]pyridines, pyridazin-3(2/7)-ones, and [fo]-fused azolo- and azinopyridazines. The Stanovnik group have studied the further transformations of the products and reviews of this chemistry are available. In a typical example, the reaction of 6-chlorotetrazolo[l,5-/7]pyridazine (37) with 2-diazopropane yields the NH,NH-dihy-dro-pyrazolo[4,3-(i]tetrazolo[l,5-/7]pyridazine 38 (102) (Scheme 8.11). The latter substrate reacts with acetone to produce an azomethine imine 39 that thermally rearranges to give the fused dihydro-1,2-diazepine 40. The azomethine imine obtained with glucose can be trapped with methyl acrylate to furnish the C-nucleoside 41 (103). 

As an extension of this chemistry, 7V-sulfinyl aziridine 188, prepared from (/ )-187, was utilized in the asymmetric synthesis of protein kinase C inhibitor D-e/yf/iro-sphingosine 189" and in the first enantioselective synthesis of the marine cytotoxic antibiotic (/ )-(-)-dysidazirine (190).100 This latter result constitutes the first general method for preparing nonracemic 2//-azirines, the smallest of the unsaturated nitrogen heterocycles.100,101... 

This chapter is concerned with all compounds having a three-mcmbered ring containing two carbon atoms and one nitrogen atom. The parent compound of this heterocyclic system is the unsaturated ring, which has two isomeric forme, I-azirine (1) and 2-azirine (IJ). Very few authentic examples of the azirines are known, and this review ib therefore concerned almost wholly with the chemistry of the saturated derivative, aziridine (111). 

A heterocycle is a compound with a ring that has more than one kind of atom. Nitrogen, oxygen, and sulfur are often found along with carbon in heterocyclic rings. Saturated heterocyclic amines, ethers, and sulfides usually have the same chemistry as their open-chain analogs, but unsaturated heterocycies such as pyrrole, furan, and thiophene are aromatic. All three are unusually stable, and all three undergo aromatic substitution on reaction with electrophiles. 

This chapter is one of the first attempts of systematic review of the synthetic methods and chemistry of nonaromatic saturated and unsaturated perfluorinated heterocycles. It summarizes data on the synthesis and chemical transformation of perfluorinated six- and to some extent five- membered nonaromatic heterocyclic compounds containing oxygen, nitrogen, sulfur, selenium, and phosphorous. It should be pointed out that the review is not all-inclusive one, but it is an attempt to provide representative examples of synthetic methods and chemistry of perfluorinated nonaromatic hetero-cychc materials. 

My interests include the chemistry of alkynes, the synthesis and reactivity of unsaturated heteroatomic compounds, as well as nitrogen-containing heterocyclic compounds. 

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