Iron‐Catalyzed C–H Bond Functionalization for the Exclusive Synthesis of Pyrido[1,2‐a]indoles or Triarylmethanols

Abstract

The cover picture shows the crystal structure of a new, orange, Ca‐containing pigment lake derived from diazo coupling of orthanilic acid to 4‐morpholino‐2‐naphthol. The crystal structure is of a novel type in which the morpholino substituent has prevented the formation of a 1‐dimensional polymeric system, which is common to previously reported naphthol‐derived pigment lakes. The pigment has been obtained in three physical forms; as a hydrate, a DMSO solvate and as a desolvated form. Azo dyes derived from 4‐morpholino‐2‐naphthol exhibit a small hypsochromic shift but with enhanced molar absorbtivity compared with dyes derived from 2‐naphthol. This pigment lake may have application for the coloration of inks, paints and plastics. Details are discussed in the article by B. M. Heron et al. on

Iron(III) bis‐complexes of Schiff bases of S‐methyldithiocarbazates: Synthesis, structure, spectral and redox properties and cytotoxicity

“…All of the reagents 2‐benzoylpyridine, 2‐acetylpyridine, hydrazine hydrate, and anhydrous iron(III) chloride were obtained from commercial sources and used without further purification. Quinoline‐2‐carboxaldehyde, 1‐methylimidazole‐2‐carbaldehyde, and S ‐methyldithiocarbazate were prepared as reported previously. The ligands were synthesized as previously reported in the literature …”

C-H amination in the synthesis of N-heterocycles

“…The copper-catalyzed C(sp 3 )-H bond amination is effective for the synthesis of heterocyclic compounds. In 2013, Huang et al 34 described the Cu(I)-catalyzed intramolecular aerobic oxidative C-H amination of 2-aminoacetophenones (41) in the presence of 2,2′-bipyridine as the ligand, and various N-alkyl-or aryl-substituted isatins (42) were prepared in good to excellent yields ( Figure 19). In the reactions, oxidation of 41 forms the corresponding acetaldehyde (I), intramolecular nucleophilic attack of imine to aldehyde in I leads to II, and further oxidation of II provides the desired product (42).…”

A pyrone remodeling strategy to access diverse heterocycles: application to the synthesis of fascaplysin natural products

“…To demonstrate the viability of this strategy, we initially focused on converting indole–pyrone adduct 3 to the pyrido[1,2- a ]indole scaffold ( 3b , Scheme 2a )—a key structural motif present in a number of biologically active natural products including fascaplysin ( 4 , Scheme 2b ), 10 goniomitine ( 5 ), 11 and tronocarpine ( 6 ). 12 While there exists numerous methods to access this biologically relevant scaffold, 13–17 many of these tactics rely on reaction precursors with highly specific substitution patterns and, therefore, are unfortunately not general or modular. Specifically, we recognized that while heterocyclic–dienolate adducts (such as C3-substituted intermediate 3a ) have proven to be effective precursors for benzannulation processes, strategies to install dienol/dienolate functionality at C2 of 1 H -indoles lacking C3-substitution have remained elusive due to regioselectivity challenges.…”