Dataset Information

A Neutral Three-Membered 2? Aromatic Disilaborirane and the Unique Conversion into a Four-Membered BSi₂ N-Ring.

ABSTRACT: We report the design, synthesis, structure, bonding, and reaction of a neutral 2? aromatic three-membered disilaborirane. The disilaborirane is synthesized by a facile one-pot reductive dehalogenation of amidinato-silylene chloride and dibromoarylborane with potassium graphite. Despite the tetravalent arrangement of atoms around silicon, the three-membered silicon-boron-silicon ring is aromatic, as evidenced by NMR spectroscopy, nucleus independent chemical shift calculations, first-principles electronic structure studies using density functional theory (DFT) and natural bond orbital (NBO) based bonding analysis. Trimethylsilylnitrene, generated in?situ, inserts in the Si-Si bond of disilaborirane to obtain a four-membered heterocycle 1-aza-2,3-disila-4-boretidine derivative. Both the heterocycles are fully characterized by X-ray crystallography.

SUBMITTER: Sarkar SK

PROVIDER: S-EPMC7756765 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature

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Publications

A Neutral Three-Membered 2π Aromatic Disilaborirane and the Unique Conversion into a Four-Membered BSi<sub>2</sub> N-Ring.

Sarkar Samir Kumar SK Chaliha Rinkumoni R Siddiqui Mujahuddin M MM Banerjee Samya S Münch Annika A Herbst-Irmer Regine R Stalke Dietmar D Jemmis Eluvathingal D ED Roesky Herbert W HW

Angewandte Chemie (International ed. in English) 20201012 51

We report the design, synthesis, structure, bonding, and reaction of a neutral 2π aromatic three-membered disilaborirane. The disilaborirane is synthesized by a facile one-pot reductive dehalogenation of amidinato-silylene chloride and dibromoarylborane with potassium graphite. Despite the tetravalent arrangement of atoms around silicon, the three-membered silicon-boron-silicon ring is aromatic, as evidenced by NMR spectroscopy, nucleus independent chemical shift calculations, first-principles e ...[more]

PMID: 32840959

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Project description:Ring cleavage dioxygenases catalyze the critical ring-opening step in the catabolism of aromatic compounds. The archetypal filamentous fungus Aspergillus niger previously has been reported to be able to utilize a range of monocyclic aromatic compounds as sole sources of carbon and energy. The genome of A. niger has been sequenced, and deduced amino acid sequences from a large number of gene models show various levels of similarity to bacterial intradiol ring cleavage dioxygenases, but no corresponding enzyme has been purified and characterized. Here, the cloning, heterologous expression, purification, and biochemical characterization of four nonheme iron(III)-containing intradiol dioxygenases (NRRL3_02644, NRRL3_04787, NRRL3_05330, and NRRL3_01405) from A. niger are reported. Purified enzymes were tested for their ability to cleave model catecholate substrates, and their apparent kinetic parameters were determined. Comparisons of k cat /Km values show that NRRL3_02644 and NRRL3_05330 are specific for hydroxyquinol (1,2,4-trihydroxybenzene), and phylogenetic analysis shows that these two enzymes are related to bacterial hydroxyquinol 1,2-dioxygenases. A high-activity catechol 1,2-dioxygenase (NRRL3_04787), which is phylogenetically related to other characterized and putative fungal catechol 1,2-dioxygenases, was also identified. The fourth enzyme (NRRL3_01405) appears to be a novel homodimeric Fe(III)-containing protocatechuate 3,4-dioxygenase that is phylogenetically distantly related to heterodimeric bacterial protocatechuate 3,4-dioxygenases. These investigations provide experimental evidence for the molecular function of these proteins and open the way to further investigations of the physiological roles for these enzymes in fungal metabolism of aromatic compounds.IMPORTANCE Aromatic ring opening using molecular oxygen is one of the critical steps in the degradation of aromatic compounds by microorganisms. While enzymes catalyzing this step have been well-studied in bacteria, their counterparts from fungi are poorly characterized despite the abundance of genes annotated as ring cleavage dioxygenases in fungal genomes. Aspergillus niger degrades a variety of aromatic compounds, and its genome harbors 5 genes encoding putative intracellular intradiol dioxygenases. The ability to predict the substrate specificities of the encoded enzymes from sequence data are limited. Here, we report the characterization of four purified intradiol ring cleavage dioxygenases from A. niger, revealing two hydroxyquinol-specific dioxygenases, a catechol dioxygenase, and a unique homodimeric protocatechuate dioxygenase. Their characteristics, as well as their phylogenetic relationships to predicted ring cleavage dioxygenases from other fungal species, provide insights into their molecular functions in aromatic compound metabolism by this fungus and other fungi.

Dataset Information

A Neutral Three-Membered 2? Aromatic Disilaborirane and the Unique Conversion into a Four-Membered BSi₂ N-Ring.

Publications

A Neutral Three-Membered 2π Aromatic Disilaborirane and the Unique Conversion into a Four-Membered BSi<sub>2</sub> N-Ring.

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Dataset Information

A Neutral Three-Membered 2? Aromatic Disilaborirane and the Unique Conversion into a Four-Membered BSi2 N-Ring.

Publications

A Neutral Three-Membered 2π Aromatic Disilaborirane and the Unique Conversion into a Four-Membered BSi<sub>2</sub> N-Ring.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

A Neutral Three-Membered 2? Aromatic Disilaborirane and the Unique Conversion into a Four-Membered BSi₂ N-Ring.