Selective skeletal editing of polycyclic arenes using organophotoredox dearomative functionalization

Reactions that lead to destruction of aromatic ring systems often require harsh conditions and, thus, take place with poor selectivities. Selective partial dearomatization of fused arenes is even more challenging but it can be a strategic approach to creating versatile, complex polycyclic frameworks. Herein we describe a general organophotoredox approach for the chemo- and regioselective dearomatization of structurally diverse polycyclic aromatics, including quinolines, isoquinolines, quinoxalines, naphthalenes, anthracenes and phenanthrenes. The success of the new method for chemoselective oxidative rupture of aromatic moieties relies on precise manipulation of the electronic nature of the fused polycyclic arenes. Experimental and computational results show that the key to overcoming the intrinsic thermodynamic and kinetic unfavorability of the dearomatization process is an ultimate hydrogen atom transfer (HAT) step, which enables dearomatization to predominate over the otherwise favorable aromatization pathway. We show that this strategy can be applied to rapid synthesis of biologically valued targets and late-stage skeletal remodeling en route to complex structures.

Integrated Microbiome–Metabolome Analysis Reveals Stage-Dependent Alterations in Bacterial Degradation of Aromatics in Leptinotarsa decemlineata

To avoid potential harm during pupation, the Colorado potato beetle Leptinotarsa decemlineata lives in two different habitats throughout its developmental excursion, with the larva and adult settling on potato plants and the pupa in soil. Potato plants and agricultural soil contain a specific subset of aromatics. In the present study, we intended to determine whether the stage-specific bacterial flora plays a role in the catabolism of aromatics in L. decemlineata. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of the operational taxonomic units (OTUs) obtained by sequencing of culture-independent 16S rRNA region enriched a group of bacterial genes involved in the elimination of mono- and polycyclic aromatics at the pupal stage compared with those at the larval and adult periods. Consistently, metabolome analysis revealed that dozens of monoaromatics such as styrene, benzoates, and phenols, polycyclic aromatics, for instance, naphthalene and steroids, were more abundant in the pupal sample. Moreover, a total of seven active pathways were uncovered in the pupal specimen. These ways were associated with the biodegradation of benzoate, 4-methoxybenzoate, fluorobenzoates, styrene, vanillin, benzamide, and naphthalene. In addition, the metabolomic profiles and the catabolism abilities were significantly different in the pupae where their bacteria were removed by a mixture of three antibiotics. Therefore, our data suggested the stage-dependent alterations in bacterial breakdown of aromatics in L. decemlineata.

Selective dealkylation of alkyl polycyclic aromatic hydrocarbons towards innovative upgrading process of practical heavy oil

A silica-monolayer loaded on alumina with weak Brønsted acid sites and large pore size can selectively dealkylate alkyl polycyclic aromatics to long-chain alkanes and polycyclic aromatics for production of chemicals and fuel.