Untersuchungen zur Chemie von Isoindolen und Isoindoleninen, XXXII [1] Elektrophile Substitutionsreaktionen von 2-Aryl-2H-isoindolen mit Trifluoressigsäureanhydrid / Studies on the Chemistry of Isoindoles and Isoindolenines, XXXII [1] Electrophilic Substitution Reactions of 2-Aryl-2H-isoindoles with Trifluoroacetic Anhydride

Abstract

<jats:p>The reaction of 2-aryl-2H-isoindoles with trifluoroacetic anhydride in pyridine leads to the formation of the corresponding 1-trifluoroacetyl-2-aryl-2H-isoindoles with acceptable yields. 1-Alkylthio-2-aryl-2H-isoindoles can be generated from 3-alkylthio-2-aryl-1 H-isoindolium-tri-fluoromethanesulfonates with pyridine and acylated in the same manner. Protonation occurs at 1-position and yields isolable 1H-isoindolium salts.</jats:p>

Rearrangement of o-(pivaloylaminomethyl)benzaldehydes: an experimental and computational study

“…As regards the minor dimer-like product 23b, the high-resolution mass spectrum proposed exactly the same molecular formula as for 23a. The 1 H and 13 C spectra taken in CDCl 3 solution also exhibited several similar chemical shifts to those obtained for 23a, but some interesting differences were also detected. The δNH = 8.50 ppm chemical shift in 23b indicates a weaker hydrogen bond, compared to the value of 9.39 ppm obtained for 23a [27].…”

“…The mechanism proposed for the formation of the intermediates 15a , b and 17a , b is supported by the fact that electrophilic substitution reactions of isoindole are well known in the literature [ 3 , 13 – 18 ] and these are analogous to that suggested for the dimerization of indole under acidic conditions ( Scheme 7 ) [ 8 ]. Electrophilic attack of indole protonated at position 3 toward the position 3 of another indole molecule, followed by deprotonation affords dimer-like derivative 20 .…”

“…IR spectra were obtained on a Bruker ALPHA FT-IR spectrometer (Billerica, MA, USA) in KBr pellets. 1 H NMR, 13 C NMR, DeptQ, Dept-135, edHSQC, selective HSQC, HMBC, selective HMBC, NOESY, 1 H, 1 H-COSY, onedimensional selective NOE, and selective TOCSY spectra were recorded at 295 K on a Bruker Avance III HD 600 (Billerica, MA, USA; 600 and 150 MHz for 1 H and 13 C NMR spectra, respectively) spectrometer equipped with a Prodigy cryo-probehead. The pulse programs were taken from the Bruker software library (TopSpin 3.5) and full 1 H and 13 C assignments were achieved with widely accepted strategies [34,35].…”

“…The lists of the NMR signals can be found in Supporting Information File 1. To facilitate the understanding of the 1 H and 13 C signal assignments, the structures of the com-pounds are also depicted on the spectra (Supporting Information File 1 pages S3-S43). High-resolution mass spectra were recorded on a Bruker O-TOF MAXIS Impact mass spectrometer (Billerica, MA, USA) coupled with a Dionex Ultimate 3000 RS HPLC (Sunnyvale, CA, USA) system with a diode array detector.…”

“…The structure elucidation of compounds 3a [1], 3b, 8a,b, and 23a,b was based on the molecular formula obtained from HRMS, comprehensive 1 H and 13 C NMR study and on the single-crystal X-ray structure of compounds 3a [1], 3b, 8b, 23a, and 23b (for spectra and detailed interpretation, see Supporting Information File 1). According to the single-crystal X-ray experiments of compounds 3b, 8b, and 23a, the solid-phase structures are stabilized by a hydrogen bond between the amide NH and the carbonyl oxygen atom of the other amide group.…”