Nitrofurans heterocyclic derivatives

Many workers have studied the preparation of nitrofuran derivatives in which the nitrofuryl group is joined directly to the heterocyclic ring. The following examples illustrate the various procedures for synthesizing these molecules ... 

Five-membered aromatic heterocycles, thiophenes, furans, pyrroles, and other jt-excessive systems are reluctant, of course, to react with nucleophilic reagents. Contrary to that, nitro- or aza-activated derivatives of azoles undergo nucleophilic displacement of hydrogen rather smoothly. A great deal of both oxidative Sn (AO) and eliminative Sn (AE) reactions in the series of nitroazoles (nitropyrrole, nitrofuran, nitrothiophene) or aza-activated azoles (imidazoles, thia-zoles, oxazoles), as well as their benzo analogues, have been documented in the literature [10-18, 45, 123-128]. 

This reasoning is supported by the observation that the reaction of 2-nitrofuran with trichloromethyl carbanion proceeds in both 3- and 5-positions, because in this case the base-induced p-elimination of HCl from the intermediate o adducts is a fast process [54]. Also the VNS reactions of nitro derivatives of other 5-membered heterocycles, imidazoles [20, 56] and thiazoles [34], with a variety of a-halogeno carbanions have been shown to proceed efficiently. 

Other Types of Nitrofurans 1. 5-Nitrofurylbutadienyl heterocyclic compounds The butadienyl derivatives, which are similar to panfuran, have been investigated and have the following formula ... 

The antischistosome activity of nitrofuran compounds was further investigated. Comparison of 3-(5-nitro-2-furyl)-substituted derivatives of propionic, acrylic and propiolic acids showed that a vinyl group is necessary for activity.1 5 in derivatives of 3-(5-nitro-2-furyl) acrylic acid, the 5-nitro group was required for activity.12 In a group of (5-nitro-2-furyl)-vinyl heterocycles containing a weakly basic N in a specific position, both the vinyl group and the N were essential for antischistosome activity.1 ... 

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