Nitrogen nucleophiles nitro substrates

Selenolates such as Na2Se, NaSeH, PhSeNa, etc., and tellurolates such as NapTe, NaTeH, PhTeNa, etc., are excellent nucleophiles and can reduce a variety of functional groups by nucleophilic attack or single electron-transfer. On treatment with alkali metal selenolates (or amine salts of HpSe and PhSeH), reduction or reductive selenation of ketones and aldehydes, C=C reduction of a,/l-unsaturated compounds, and reduction of nitrogen compounds such as nitro compounds occur successfully [118, 176]. Compared with these selenolate anions, the corresponding tellurium compounds are highly reactive not only toward the same substrates but also toward halo compounds such as a-bromo ketones and vic-dibromoalkanes [46, 52, 177]. 

In most cases, nitrothiophenes or bromo-substituted nitrothiophenes have been used as the substrates for aromatic nucleophilic substitutiOTi. Both bromo and nitro groups can be substituted by oxygen, nitrogen or sulfur nucleophiles [156]. 

In the synthesis of goniomitine, an intramolecular nucleophilic addition of the indolyl nitrogen N1 to C21 of the putative iminium intermediate 15 was assumed to be the last step of tORC sequence [55]. However, authors noticed that an alternative cyclization via nucleophilic addition of C7 (supposed to be more nucleophilic than Nl) to C21 was not observed, most probably for steric reasons (Scheme 14.4). To channel the cyclization via the formation of the C7-C21 bond, authors planned to impose a geometric constraint by introducing a C5-N4 bond into the IROC substrate. As expected, with the C5-N4 connected intermediate 17 in hand, authors successfully used the IROC reaction to finish the synthesis of ( )-dehydroaspermidine in a beautiful step. Reduction of the nitro group with TiClj in an ammonium... 

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