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A nucleophilic aromatic substitution (S N Ar) is a substitution reaction in organic chemistry in which the nucleophile displaces a good leaving group, such as a halide, on an aromatic ring. Aromatic rings are usually nucleophilic, but some aromatic compounds do undergo nucleophilic substitution.
Nucleophilic addition reactions of nucleophiles with electrophilic double or triple bond (π bonds) create a new carbon center with two additional single, or σ, bonds. [1] Addition of a nucleophile to carbon–heteroatom double or triple bonds such as >C=O or -C≡N show great variety.
The half-sandwich complex in the Dötz reaction can be demetallated to give corresponding aryl product, or it could be further employed for a nucleophilic addition to aromatic system strategy for synthesis of fully-substituted benzene ring. [14] The Dötz reaction has been employed in the syntheses of natural products, as illustrated below. [15 ...
Radical-nucleophilic aromatic substitution Bunnett 1970. It now resembles ipso-substitution with 1a forming preferentially 3a and 1b forming 3b. Radical scavengers suppress ipso-substitution in favor of cine-substitution and the addition of potassium metal as an electron donor and radical initiator does exactly the opposite. [4]
Substitution reactions in organic chemistry are classified either as electrophilic or nucleophilic depending upon the reagent involved, whether a reactive intermediate involved in the reaction is a carbocation, a carbanion or a free radical, and whether the substrate is aliphatic or aromatic. Detailed understanding of a reaction type helps to ...
The Haworth synthesis is a classic method for the synthesis of polycyclic aromatic hydrocarbons. In this reaction, an arene is reacted with succinic anhydride, the subsequent product is then reduced in either a Clemmensen reduction or a Wolff-Kishner reduction. Lastly, a second Friedel-Crafts acylation takes place with addition of acid. [27]
Nucleophilic additions to arynes have been widely used in natural product total synthesis. Indeed, nucleophilic additions of arynes are some of the oldest known applications of aryne chemistry. [14] Nucleophilic addition to aryne was used in the attempted synthesis of cryptaustoline (1) and cryptowoline (2). [53]
Although aromatic resonance stabilizes aryl radicals, bonds between arenes and their substituents are (in)famously strong. Radical reactions with arenes typically present retrosynthetically as instances of nucleophilic aromatic substitution , [ citation needed ] because generating the aryl radical requires a strong (radical) leaving group.