Intramolecular nucleophilic aliphatic substitution

There have been several reports of the use of intramolecular displacements of nitro groups in the synthesis of heterocyclic compounds. Thus, reaction16 of the intermediate (2) with a strong base in DMF results in the substitution of a nitro group by the amide function to yield a dibenzothiazepinone derivative (3). Nucleophilic addition across the double bond of 2,4,6-trinitrostyrene may occur with thiophenol, aniline, and aliphatic amines. The adducts so formed with primary amines may undergo intramolecular substitution of an o-nitro group to give IV-substituted 4,6-dinitroindoles.17... 

Various aldehydes 184 and alcohols have been shown to be competent in the redox esterification of unsaturated aldehydes in the presence of the achiral mesityl triazo-lium pre-catalyst 186. Both aromatic and aliphatic enals participate in yields up to 99% (Table 13). Tri-substituted enals work well (entry 3), as do enals with additional olefins present in the substrate (entries 4 and 7). The nucleophile scope includes primary and secondary alcohols as well as phenols and allylic alcohols. Intramolecular esterification may also occur with the formation of a bicyclic lactone (entry 8). 

Intramolecular nucleophilic aromatic substitution in alkaline solution resulting in the migration of an aromatic system from one heteroatom to another. The two-carbon unit joining X and Y is usually part of an aromatic ring but may also be aliphatic ... 

Moreover, they are versatile building blocks for the synthesis of functionalized naphthalenes, anthracenes, and naphthacene natural products [8]. Recently, Rh-catalyzed C-H activation followed by nucleophilic addition to aldehydes emerged as a powerful alternative to access phthalides. In 2012, Li and coworkers developed a novel Rh(III)-catalyzed synthesis of three substituted phthalides from benzoic acids and aldehydes through carboxylate-directed ortho-C-H functionalization and subsequent intramolecular cyclization (Scheme 6.2a) [9]. In 2013, GooCen and coworkers described the straightforward synthesis of S-alkylidenephthalides from benzoic acids and aliphatic acids or anhydrides in the presence of [Rh(cod)Cl]2 and CsF (Scheme 6.2b) [10]. 

The ecofriendly solvent-free reactions of o-aminothiophenol and aromatic or aliphatic P-keto esters with microwave irradiation produced 2-substituted benzothia-zoles in excellent yields. The formation of the 2-substituted benzothiazoles probably involves the nucleophilic addition of the thiol group to the keto group of the P-keto ester followed by elimination of ethyl acetate from the resulting adduct. Then it undergoes an intramolecular addition of the o-amino group to the carbonyl group to give an adduct, from which water is eliminated to afford the 2- substituted benzothiazoles (Kamila et al., 2005). 

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