Reactions of Nitroarenes with Corey–Chaykovsky Reagents

Abstract

Electrophilic and nucleophilic substitutions of aromatic substrates share common mechanistic pathways. In both scenarios reacting species attack rings at the unsubstituted (C-H) positions, giving cationic Wheland intermediates, or anionic Meisenheimer complexes. However, the following step of rearomatization breaks the intrinsic symmetry, due to different leaving group ability of proton and hydride anion, respectively. In effect, electron-deficient arenes are prone to transformations unparalleled in electrophilic chemistry. In our article, we present transformations of anionic σH-adducts, formed between nitroarenes and carbanions of the Corey-Chaykowsky reagents. Depending on structure of the substrates and reaction conditions, the intermediates undergo cyclization to cyclopropanes (benzonorcaradienes), or base-induced elimination to the alkylated products. Mechanistic studies reveal that order of the carbanions controls competition between the processes, due to steric hindrance developing at the β-elimination step. 1 Introduction 2 Cyclopropanation of Nitronaphthalenes 3 Alkylation of Nitropyridines 4 Mechanistic Studies 5 Conclusion and Outlook

A new method for synthesizing terminal olefins from esters using the Corey–Chaykovsky reagent

“…1a). [10][11][12][13] Conventional strategies for constructing terminal olefin functional groups include the venerable Wittig reaction, 14,15 semi-hydrogenation of terminal alkynes, [16][17][18][19] and derivatization of uncomplicated olefins. [20][21][22] Furthermore, selective removal of specific fragments, such as aldehydes, 23 nitriles, 24 carboxylic acids, [25][26][27] and their activated derivatives from the feedstock, [28][29][30] serves as an interesting approach in this field (Fig.…”

“…Surprisingly, the Michael addition did not occur. Instead, a new single product was obtained in high yield, which was identified as methyl(((4-phenylbuta-1,3-dien-2-yl)oxy)methyl) sulfane (3q) by 13 C NMR, 1 H NMR, 13 C-DEPT135, and HRMS analysis.…”