Benzocyclobutenes. Part 4. Synthesis of benzocyclobutene-1,2-diones by pyrolytic methods

The Synthesis of Novel Isoindoline Nitroxides Bearing Water‐Solubilising Functionality

“…Thus, we prepared 4,5-dibromophthalic anhydride (16) by permanganate oxidation of 4,5-dibromo-o-xylene and subsequent cyclisation of the diacid using established literature procedures. [30] The anhydride 16 was easily converted into the corresponding phthalimide 15 (Scheme 4) using benzylamine in acetic acid in good yield (70 %), however attempted ethylation of 15 using EtMgI in toluene gave a complex mixture which contained neither the desired product 17 nor the starting material 15. Following this reaction, it was decided that the ethyl groups must be introduced prior to bromination of the aromatic ring.…”

“…Triethylamine and pyridine were dried by storage with potassium hydroxide. Crystalline K 4 [Fe(CN) 6 ]·3H 2 O was ground to a fine powder and then dried at 80°C at 0.5 Torr for 10 h. 2-Benzyl-1,1,3,3-tetraethylisoindoline [36] (7), 2-benzyl-1,1,3,3-tetramethylisoindoline [37] (10), 4,5-dibromophthalic anhydride [30] (16), 4,5-dimethylphthalic anhydride [30,33,34] (22) and 5-bromo-1,1,3,3-tetramethylisoindoline [25] (43) were prepared using established literature procedures. All other reagents were purchased from commercial suppliers and used without further purification.…”

Hydrogen Atom Transfer (HAT) Processes Promoted by the Quinolinimide-N-oxyl Radical. A Kinetic and Theoretical Study

“…Acetonitrile (HPLC grade), NHPI, (NH 4 ) 2 Ce(NO 3 ) 6 , Mg(ClO 4 ) 2 , and HClO 4 were commercially available and used as received. NHQI was synthesized by reaction of pyridine-2,3-dicarboxylic acid anhydride 37 with hydroxylamine hydrochloride following a procedure reported in the literature. 10 Toluene, ethylbenzene, cumene, p-xylene, p-methoxytoluene, miodotoluene, 4-methylacetophenone, p-tolunitrile, cyclohexane, adamantane, methanol, ethanol, 2-propanol, tetrahydrofuran, N,Ndimethylformamide, and p-chlorobenzaldehyde were commercially available at their highest purity and used as received.…”

A simple preparation of ethyl 2,5‐dimethylfuran‐3‐carboxylate and 2,5‐dimethylfuran‐3,4‐dicarboxylic acid from diethyl 2,3‐diacetylsuccinate

“…Its derivatives have been used as wood preservatives [3], microbicides, insecticides [4], and fungicides [5]. 2,5-Dimethylfuran-3,4-dicarboxylic acid (4) and diethyl 2,5-dimethylfuran-3,4-dicarboxylate (5) are also useful intermediates in medicinal chemistry and organic synthesis [6][7][8]. Among the different approaches to multiply substituted furans [9][10][11][12][13][14][15], there are some methods for the preparation of 3, such as gold(I) catalyzed cascade reaction of propargyl Claisen rearrangement and heterocyclization of propargyl vinyl ethers [1], polymer-supported selenium-induced electrophilic cyclization [16], I 2 -induced cyclization of 2-alkenyl substituted 1,3-dicarbonyl compounds [17], treatment of a,b-unsaturated ketones with N-bromosuccinimide followed by cyclization [18], and treatment of ethyl 2-acetyl-4-oxopentanoate with montmorillonite clay in toluene at reflux with water removal [5].…”