An overview of the reactions involving azomethine imines over half a decade

Azomethine imines constitute a versatile class of 1,3-dipoles which was used extensively for biologically relevant N-heterocycle synthesis – a five-year recap.

Potassium tert-butoxide mediated C-C, C-N, C-O and C-S bond forming reactions

Potassium tertiary butoxide (KO^tBu) mediated constructions of C-C, C-O, C-N, and C-S bonds are reviewed with special emphasis on their synthetic applications. KO^tBu can be used to perform reactions already known to be carried out using transition metals, but it has advantages in terms of environmental congruence and economic cost. KO^tBu is widely employed in organic synthesis to mediate the construction of C-C, C-O, C-N, C-S and miscellaneous bonds in good to excellent yields. Synthetic uses of KO^tBu in coupling, alkylation, arylation, α-phenylation, cyclization, Heck-type, annulation, photo-arylation, aromatic-substitution, amidation, and silylation reactions are summarized and discussed. The mechanisms through which KO^tBu carries out a specific reaction are also discussed. One of the goals of this review is to attract the attention of chemists as to the benefits of using KO^tBu as an environmentally benign alternative to transition metals and its applications in the construction of chemical bonds with predominant importance in organic synthesis. This review completely covers the synthetic protocols that have been performed using KO^tBu in the last two decades.

Brønsted Acid-Catalyzed (4 + 3) Cyclization of N, N'-Cyclic Azomethine Imines with Isatoic Anhydrides

A Brønsted acid-catalyzed (4 + 3) cyclization of N, N'-cyclic azomethine imines with isatoic anhydrides has been discovered, which constructs seven-membered nitrogenous heterocyclic frameworks with overall high yields (up to 98% yield). This reaction represents a rarely reported (4 + 3) cyclization of N, N'-cyclic azomethine imines, which involves the reassembly of a C-N bond. In addition, this reaction has also accomplished the unprecedented (4 + 3) cyclization of isatoic anhydrides.