Aqueous olefin metathesis: recent developments and applications

• Valerio Sabatino and
• Thomas R. Ward

Beilstein J. Org. Chem. 2019, 15, 445–468, doi:10.3762/bjoc.15.39

• biohybrid catalysts able to catalyze all three main olefin metathesis reactions (RCM, ROMP and CM) [72]. Schwaneberg and Okuda engineered the cavity size of the β-barrel protein nitrobindin (variant 4, NB4) to accommodate HG-type catalysts. The authors followed a similar approach developed earlier with a

• variant of the β-barrel protein FhuA [73][74]. To do so, the authors duplicated multiple β-barrel strands to enlarge the cavity of the protein. HG-type catalysts bearing a maleimide moiety with different spacer lengths (69–71) were covalently anchored to a cysteine of the expanded nitrobindin variant

• entry 1SHS. Artificial metathases based on cavity-size engineered β-barrel protein nitrobindin (NB4exp). The HG-type catalysts 69, 70 and 71 are located inside nitrobindin to afford ArM 5, ArM 6 and ArM 7. Artificial metathase based on cutinase (ArM 8) and resulting metathesis activities. Site-specific

Olefin metathesis catalysts embedded in β-barrel proteins: creating artificial metalloproteins for olefin metathesis

• Daniel F. Sauer,
• Johannes Schiffels,
• Takashi Hayashi,
• Ulrich Schwaneberg and
• Jun Okuda

Beilstein J. Org. Chem. 2018, 14, 2861–2871, doi:10.3762/bjoc.14.265

• and challenges and opportunities in this emerging field are shown from simple small-molecule transformations over ring-opening metathesis polymerizations to in vivo olefin metathesis. Keywords: artificial metalloprotein; β-barrel protein; metathease; olefin metathesis; ruthenium; Introduction Olefin

• synthesized by Ward [29]. A GH-type second generation olefin metathesis catalyst was modified at the periphery of an NHC ligand with a biotin moiety [46]. The small β-barrel protein avidin (Avi) or streptavidin (Sav) was incubated with the catalyst to give the artificial metalloprotein. This (strept)avidin

• (NB) is a small, soluble β-barrel protein with a molecular weight of 19 kDa [49]. NB wild-type has 10 β-strands and contains a heme as a prosthetic group [49]. Upon modification of the axial histidine that coordinates the heme, the robust β-barrel structure with a relatively small cavity is retained

2-Methyl-2,4-pentanediol (MPD) boosts as detergent-substitute the performance of ß-barrel hybrid catalyst for phenylacetylene polymerization

• Julia Kinzel,
• Daniel F. Sauer,
• Marco Bocola,
• Marcus Arlt,
• Tayebeh Mirzaei Garakani,
• Andreas Thiel,
• Klaus Beckerle,
• Tino Polen,
• Jun Okuda and
• Ulrich Schwaneberg

Beilstein J. Org. Chem. 2017, 13, 1498–1506, doi:10.3762/bjoc.13.148

• using the robust β-barrel protein nitrobindin. The selectivity in the polymerization of phenylacetylene was influenced with the protein as second ligand sphere [12][13]. The catalyst achieved a cis/trans ratio of 91:9 in the organic solvent tetrahydrofuran (THF) or being bound on a protein surface

• generate artificial whole-cell catalysts. Nevertheless, the productivity with a turnover number of 6 (with respect to the metal content) is yet low [4]. Here, we present a new strategy based on the robust β-barrel protein Ferric hydroxamate uptake protein component A (FhuA, Tm 60–65 °C, refolding after

Artificial Diels–Alderase based on the transmembrane protein FhuA

• Hassan Osseili,
• Daniel F. Sauer,
• Klaus Beckerle,
• Marcus Arlt,
• Tomoki Himiyama,
• Tino Polen,
• Akira Onoda,
• Ulrich Schwaneberg,
• Takashi Hayashi and
• Jun Okuda

Beilstein J. Org. Chem. 2016, 12, 1314–1321, doi:10.3762/bjoc.12.124

• , MALDI–TOF–MS, ThioGlo fluorescence titration, and BCA assay. All employed methods indicate the folded structure of FhuA ΔCVFtev and a high occupancy of the only accessible cysteine residue within this β-barrel protein. The biohybrid catalysts showed high activity and high endo selectivity in the Diels