Schönau am Königssee, Germany
Schönau am Königssee, Germany

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Braunschweig H.,Julius Maximilians University Wu rzburg | Ewing W.C.,Julius Maximilians University Wu rzburg | Geetharani K.,Julius Maximilians University Wu rzburg | Schafer M.,Julius Maximilians University Wu rzburg
Angewandte Chemie - International Edition | Year: 2015

The first examples of adducts of cyclic alkyl(amino) carbenes (CAAC) and N-heterocyclic carbenes (NHCs) with iminoboranes have been synthesized and isolated at low temperature (-45°C). The adducts show short B=N bonds and planarity at boron, mimicking the structures of the isoelectronic imine functionality. When di-tert-butyliminoborane was reacted with 1,3-bis(isopropyl)imidazol-2-ylidene (IPr), the initially formed Lewis acid-base adduct quickly rearranged to form a new carbene substituted with an aminoborane at the 4-position. Warming the iminoborane-CAAC adduct to room temperature resulted in an intramolecular cyclization to give a bicyclic 1,2-azaborilidine compound. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Jahn M.T.,University of East Anglia | Jahn M.T.,Julius Maximilians University Wu rzburg | Schmidt K.,University of East Anglia | Mock T.,University of East Anglia
Plant Methods | Year: 2014

Background: Marine microalgae are of major ecologic and emerging economic importance. Biotechnological screening schemes of microalgae for specific traits and laboratory experiments to advance our knowledge on algal biology and evolution strongly benefit from culture collections reflecting a maximum of the natural inter- and intraspecific diversity. However, standard procedures for strain isolation and identification, namely DNA extraction, purification, amplification, sequencing and taxonomic identification still include considerable constraints increasing the time required to establish new cultures. Results: In this study, we report a cost effective and high-throughput isolation and identification method for marine microalgae. The throughput was increased by applying strain isolation on plates and taxonomic identification by direct PCR (dPCR) of phylogenetic marker genes in combination with a novel sequencing electropherogram based screening method to assess the taxonomic diversity and identity of the isolated cultures. For validation of the effectiveness of this approach, we isolated and identified a range of unialgal cultures from natural phytoplankton communities sampled in the Arctic Ocean. These cultures include the isolate of a novel marine Chlorophyceae strain among several different diatoms. Conclusions: We provide an efficient and effective approach leading from natural phytoplankton communities to isolated and taxonomically identified algal strains in only a few weeks. Validated with sensitive Arctic phytoplankton, this approach overcomes the constraints of standard molecular characterisation and establishment of unialgal cultures. © 2014 Jahn et al.

Schneider H.,Julius Maximilians University Wu rzburg | Schmidt D.,Julius Maximilians University Wu rzburg | Radius U.,Julius Maximilians University Wu rzburg
Chemistry - A European Journal | Year: 2015

The reaction of 1,3-diisopropylimidazolin-2-ylidene (iPr2Im) with diphenyldichlorosilane (Ph2SiCl2) leads to the adduct (iPr2Im)SiCl2Ph2 1. Prolonged heating of isolated 1 at 66°C in THF affords the backbone-tethered bis(imidazolium) salt [(aHiPr2Im)2SiPh2]2+2Cl- 2 (“a“ denotes “abnormal“ coordination of the NHC), which can be synthesized in high yields in one step starting from two equivalents of iPr2Im and Ph2SiCl2. Imidazolium salt 2 can be deprotonated in THF at room temperature using sodium hydride as a base and catalytic amounts of sodium tert-butoxide to give the stable N-heterocyclic dicarbene (aiPr2Im)2SiPh2 3, in which two NHCs are backbone-tethered with a SiPh2 group. This easy-to-synthesize dicarbene 3 can be used as a novel ligand type in transition metal chemistry for the preparation of dinuclear NHC complexes, as exemplified by the synthesis of the homodinuclear copper(I) complex [{a(ClCu-iPr2Im)}2SiPh2] 4. Show some backbone: NHC to aNHC rearrangement, instead of NHC ring expansion as observed for Ph2SiH2, is the predominant pathway for the reaction of the N-heterocyclic carbene 1,3-diisopropylimidazolin-2-ylidene with Ph2SiCl2 (see Scheme; aNHC denotes “abnormal“ coordination of the NHC). This rearrangement can be utilized for novel, easy-to-synthesize, backbone-tethered dicarbene ligands. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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