Arylation of Unsaturated Compounds by Diazonium Salts (The Meerwein Arylation Reaction)

Molecular Modeling of an Electrophilic Addition Reaction with “Unexpected” Regiochemistry

“…A second model system that could also be shown at this time is acrylic acid (propenoic acid), demonstrating how considering this system simply as an alkene would lead to the conclusion that 2-chloropropanoic acid should be the product of the reaction with HCl, whereas the literature states that the product is 3-chloropropanoic acid. , If this second model system is presented, the experiment could then be framed as an exploration of whether atropic acid behaves like styrene (because of resonance in the carbocation intermediate) or like acrylic acid, as well as why both acrylic acid and atropic acid would produce products that do not seem to follow the rules that students have learned to this point in organic chemistry.…”

“…The data obtained from the modeling suggest that the O-protonated carbocation intermediate produced by the 1,4-addition is the most stable, leading to the observed product with the halogen attached to C3. Acrylic acid is known to undergo addition of HCl at the β-position as well to give 3-chloropropanoic acid, , suggesting that atropic acid should be considered an acrylic acid derivative rather than a styrene derivative. Further support for conjugate addition of HCl to unsaturated carboxylic acids can be found in this Journal …”

Arylnaphthoquinones. 7. Synthesis of angular heterocycles from 2-aryl-1,4-naphthoquinones

“…Зручним методом синтезу арилнафтохінонів є взаємодія ароматичних солей діазонію у середовищі водної мурашиної кислоти за присутності ацетату натрію в умовах каталітичної дії сполук купруму з 1,4-нафтохіноном (арилювання за Меєрвейном) [17] (схема 1). Реакція відбувається за температури 30-40 °С, виходи арилнафтохінонів 1-7 становлять 30-55 %.…”