Solvent-free preparation of primary imines from (2-hydroxyaryl)ketones

Microwave‐Promoted, One‐Pot, Solvent‐Free Synthesis of 4‐Arylcoumarins from 2‐Hydroxybenzophenones

“…So, benzophenone 1a was trans-4-Arylcoumarins from 2-Hydroxybenzophenones by Microwave Irradiation formed into corresponding imine 2 following the method described by Perlmutter et al [30] for benzophenones with a hydroxy group at the 2-position. The procedure is very simple and is carried out in the absence of solvent, [31] providing 50 % yield of the product.…”

Characterization and Utility of N‐Unsubstituted Imines Synthesized from Alkyl Azides by Ruthenium Catalysis

“…For example, Chen and Brown, [5] and Itsuno et al [6] suggested that N-unsubstituted imines could be formed from the N-trialkylsilyl imine precursors, but the scope of this method is restricted to the preparation of non-enolizable imines. In addition, N-unsubstituted imines are not generally obtained as a stable entity in the conventional reaction of carbonyl compounds with ammonia (only limited examples such as ortho-hydroxyarylketimines are known to be stable under these reaction conditions) [7] . Recently, Kobayashi and co-workers [8] and Thadani and coworkers [9] reported the aminoallylation of carbonyl compounds in one-pot, wherein the N-unsubstituted imines were not detected, but proposed as plausible intermediates.…”

“…unsubstituted imines from benzyl azide. Notably, even the borane complex of the aliphatic N-unsubstituted aldimine 14 could be obtained from 9 in high yield [Eq (7); the characteristic doublet peak at d = 8.87 ppm was assigned to the imino hydrogen atom).…”

Solventless Synthesis of Imines Derived from Diphenyldisulphide Diamine or p‐Vanillin

“…These types of compounds have normally been synthesized by traditional methods using organic solvents. Recently, a few papers reported modern synthetic protocols where benign solvents (water or supercritical CO 2 ) 4,5 , recyclable reactions medium (PPG) 6 and solvent-less conditions [7][8][9][10] have been used. These conditions are so simple as to be considered almost facile yet generate products in good yields, which give them attractive green chemistry metrics.…”