Derivatives of Aromatic Heterocyclic Compounds

Patent Diazirine Derivatives of Aromatic Heterocyclic Compounds 

Baird etal, US Patent 5,120,861 (June 9, 1992) Assignee Shell Research Limited Utility Halodiazirine and Cyclopropane Derivatives 

The diazirine from Step 1 (9.5 mmol) was dissolved in methylacrylate (90 mmol) and 10 ml tetrachloroethylene then refluxed 20 minutes. The crude products consisted of an isomeric cyclopropane mixture with a syn/anti ratio of 3.8 1. The mixture was purified by chromatography on silica with light petroleum/EtOAc, 5 1, and the product mixture isolated 68% yield with no change in the isomer ratio. H-NMR and data supplied. 

This is an example of the Graham diazine synthesis (1) as illustrated in Eq. 1  

Diazirines are thermally unstable and generate a carbine radical intermediate. This property has been used with hydrazones as a route for forming cyclopropanes (2) as illustrated in Eq. 2  

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Mononitro derivatives of aromatic heterocyclic compounds and condensed aromatic systems behave as described for benzene derivatives. As in the benzene series, any prediction of the most likely reaction route for a given compound must be based upon considerations of the reactivity of the compound and its reduction products in the different types of reactions possible under a given set of parameters. 

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