Electro-Oxidative Synthesis of Phenazines

We disclose herein electro-oxidative synthesis as the general protocol for procuring phenazines under mild reaction conditions. Using aerial oxygen as an oxidant, inexpensive electrolyte, and electrodes, a diverse range of phenazines have been accessed in good yields via the ring contraction of 10,11-dihydro-5H-dibenzo[b,e][1,4]diazepines. In addition, the syntheses of phenazines and diamino phenazines via direct electro-oxidation of dihydrophenazines and electro-dimerization of o-phenylenediamines, respectively, have also been accomplished.

Switching the Regioselectivity Access to Pyrroles and Isoquinolines from Ketoxime Acetates and Ynals

A novel formal [3+2] and [4+2] annulation of ketoxime acetates and ynals for the synthesis of pyrroles and isoquinolines has been developed. By simply switching the catalyst and solvent, the reaction proceeds via two pathways. The reactions are achieved under mild conditions with broad substrate scope and excellent regioselectivity.

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.