Benzidine Rearrangement Reactions of Polyether Tethered Cyclic N,N‘-Diaryl Hydrazides

Recent trends in the chemistry of Sandmeyer reaction: a review

Metal-catalyzed reactions play a vital part to construct a variety of pharmaceutically important scaffolds from past few decades. To carry out these reactions under mild conditions with low-cost easily available precursors, various new methodologies have been reported day by day. Sandmeyer reaction is one of these, first discovered by Sandmeyer in 1884. It is a well-known reaction mainly used for the conversion of an aryl amine to an aryl halide in the presence of Cu(I) halide via formation of diazonium salt intermediate. This reaction can be processed with or without copper catalysts for the formation of C-X (X = Cl, Br, I, etc.), C-CF₃/CF₂, C-CN, C-S, etc., linkages. As a result, corresponding aryl halides, trifluoromethylated compounds, aryl nitriles and aryl thioethers can be obtained which are effectively used for the construction of biologically active compounds. This review article discloses various literature reports about Sandmeyer-related transformations developed during 2000-2021 which give different ideas to synthetic chemists about further development of new and efficient protocols for Sandmeyer reaction. An updated compilation of new approaches for Sandmeyer reaction is described in this review to construct a variety of carbon-halogen, carbon-phosphorous, carbon-sulfur, carbon-boron etc. linkages.

Copper-catalyzed intermolecular oxidative trifluoromethyl-arylation of styrenes with NaSO2CF3 and indoles involving C–H functionalization

A new copper-catalyzed three-component oxidative 1,2-trifluoromethylarylation of styrenes with NaSO₂CF₃ and indoles involving aryl C–H bond functionalization is described.

Reagent- and Metal-Free Anodic C-C Cross-Coupling of Aniline Derivatives

The dehydrogenative cross-coupling of aniline derivatives to 2,2'-diaminobiaryls is reported. The oxidation is carried out electrochemically, which avoids the use of metals and reagents. A large variety of biphenyldiamines were thus prepared. The best results were obtained when glassy carbon was used as the anode material. The electrosynthetic reaction is easily performed in an undivided cell at slightly elevated temperature. In addition, common amine protecting groups based on carboxylic acids were employed that can be selectively removed under mild conditions after the cross-coupling, which provides quick and efficient access to important building blocks featuring free amine moieties.

Selected synthetic strategies to cyclophanes

In this review we cover various approaches to meta- and paracyclophanes involving popular reactions. Generally, we have included a strategy where the reaction was used for assembling the cyclophane skeleton for further functionalization. In several instances, after the cyclophane is made several popular reactions are used and these are not covered here. We included various natural products related to cyclophanes. To keep the length of the review at a manageable level the literature related to orthocyclophanes was not included.

N2,N2′-Bis(2,2-dimethylpropanoyl)benzene-1,3-dicarbohydrazide

In the mol­ecular structure of the title hydrazide derivative, C₁₈H₂₆N₄O₄, the conformations of the two units of 2-(2,2-dimethyl-1-oxoprop­yl)hydrazide substituents are not planar; these two units are attached axially to the benzene ring with C(ortho)—C—C(=O)—N torsion angles of 28.1 (2) and 31.0 (2)° [where C(ortho) is the C atom at position 4 of the benzene ring relative to the substituent at position 3 or the C atom at position 6 of the benzene ring relative to the substituent at position 1, as appropriate]. The dihedral angles between the hydrazide units and the benzene ring are 62.66 (7) and 63.84 (7)°. In the crystal structure, mol­ecules are arranged in an anti-parallel manner and are linked by N—H⋯O inter­molecular hydrogen bonds and weak C—H⋯O inter­molecular inter­actions into a three-dimensional network. The structure is further stabilized by a weak C—H⋯N intra­molecular inter­action.