Enroute sustainability: metal free C-H bond functionalisation

The term "C-H functionalisation" incorporates C-H activation followed by its transformation. In a single line, this can be defined as the conversion of carbon-hydrogen bonds into carbon-carbon or carbon-heteroatom bonds. The catalytic functionalisation of C-H bonds using transition metals has emerged as an atom-economical technique to engender new bonds without activated precursors which can be considered as a major drawback while attempting large-scale synthesis. Replacing the transition-metal-catalysed approach with a metal-free strategy significantly offers an alternative route that is not only inexpensive but also environmentally benign to functionalize C-H bonds. Recently metal free synthetic approaches have been flourishing to functionalize C-H bonds, motivated by the search for greener, cost-effective, and non-toxic catalysts. In this review, we will highlight the comprehensive and up-to-date discussion on recent examples of ground-breaking research on green and sustainable metal-free C-H bond functionalisation.

Ni-Catalysed intramolecular reductive aminocarbonylation of 2-haloaryl-tethered nitroarenes for the synthesis of dibenzazepine-based heterocycles

A nickel-catalysed intramolecular reductive aminocarbonylation of 2-haloaryl-tethered nitroarenes is developed for rapid access to a variety of dibenzoazepinones and their derivatives.

Synthesis of substituted benzo[b][1,4]oxazepine derivatives by the reaction of 2-aminophenols with alkynones

We have developed a novel synthetic method accessing benzo[b][1,4]oxazepines that are one of the rare classes of benzoxazepine derivatives by reaction of 2-aminophenols with alkynones in 1,4-dioxane at 100 °C.

Genome Mining for Mycemycin: Discovery and Elucidation of Related Methylation and Chlorination Biosynthetic Chemistries

A silent dibenzoxazepinone (DBP) biosynthetic gene cluster ( myc) was mutagenically activated in Streptomyces olivaceus SCSIO T05, enabling the discovery of mycemycin C (4) and three new analogues [mycemycins F-H (1-3)]. Gene disruption, complementation experiments, and enzymatic assays unveiled salicylic acid and 5-Cl-kynurenine as biosynthetic precursors and shed significant functional insights into MycO, MycB, MycR, and MycJ, enzymes responsible for fine-tuning of the DBP scaffold.

Identification and Characterization of Mycemycin Biosynthetic Gene Clusters in Streptomyces olivaceus FXJ8.012 and Streptomyces sp. FXJ1.235

Mycemycins A–E are new members of the dibenzoxazepinone (DBP) family, derived from the gntR gene-disrupted deep sea strain Streptomyces olivaceus FXJ8.012Δ1741 and the soil strain Streptomyces sp. FXJ1.235. In this paper, we report the identification of the gene clusters and pathways’ inference for mycemycin biosynthesis in the two strains. Bioinformatics analyses of the genome sequences of S. olivaceus FXJ8.012Δ1741 and S. sp. FXJ1.235 predicted two divergent mycemycin gene clusters, mym and mye, respectively. Heterologous expression of the key enzyme genes of mym and genetic manipulation of mye as well as a feeding study in S. sp. FXJ1.235 confirmed the gene clusters and led to the proposed biosynthetic pathways for mycemycins. To the best of our knowledge, this is the first report on DBP biosynthetic gene clusters and pathways.

Organoiodine reagent-promoted intermolecular oxidative amination: synthesis of cyclopropyl spirooxindoles

An organoiodine-promoted intramolecular direct oxidative C(sp²)–N cross-coupling reaction was developed for the preparation of cyclopropyl spirooxindoles from readily available secondary cyclopropyl carboxamides.

One-pot sequential reaction to 2-substituted-phenanthridinones from N-methoxybenzamides

A one-pot synthesis of 2-bromo/chloro-phenanthridinones via an amidation of arenes followed by a regioselective halogenation reaction has been developed using a hypervalent iodine reagent.