Organische Chemie (Sparr)

Hutskalova, V. (2025) Aromatic ring-opening metathesis and development of novel photoredox- and transition metal-catalyzed (atroposelective) synthetic methods .

Lotter, Dominik et al. (2025) ‘Photoinduced Energy Transfer via an Atropisomeric Molecular Bridge’, Helvetica Chimica Acta. 04.12.2024, 108(1). Available at: https://doi.org/10.1002/hlca.202400163.

Sparr, Christof and Jana, Kalipada (2025) ‘Enantioselective Wittig Reactions Controlled by P III /P V =O Redox Catalysis’, Synlett. 03.02.2025, 36, pp. A–E. Available at: https://doi.org/10.1055/s-0043-1775441.

Hutskalova, Valeriia and Sparr, Christof (2024) ‘Aromatic ring-opening metathesis’, Nature. 11.12.2024, 638, pp. 697–703. Available at: https://doi.org/10.1038/s41586-024-08472-z.

Jana, Kalipada et al. (2024) ‘Atroposelective Arene‐Forming Wittig Reaction by Phosphorus P III /P V =O Redox Catalysis’, Angewandte Chemie. 28.06.2024, 136(37). Available at: https://doi.org/10.1002/ange.202408159.

Schmidt, Tanno A., Hutskalova, Valeriia and Sparr, Christof (2024) ‘Atroposelective catalysis’, Nature Reviews Chemistry. 18.06.2024, 8, pp. 497–517. Available at: https://doi.org/10.1038/s41570-024-00618-x.

Hutskalova, Valeriia and Sparr, Christof (2024) ‘Aromatic Ring-Opening Metathesis’, Chemrxiv [Preprint]. Cambridge University Press (Chemrxiv). Available at: https://doi.org/10.26434/chemrxiv-2024-d6qkv.

Hutskalova, V., Bou Hamdan, F. and Sparr, C. (2024) ‘Decarboxylative Nickel- and Photoredox-Catalyzed Aminocarbonylation of (Hetero)Aryl Bromides’, Organic Letters, 26(14), pp. 2768–2772. Available at: https://doi.org/10.1021/acs.orglett.3c02389.

Buchholz, T.A. (2024) Helically-shaped peri-oligo-naphthylenes and organophotocatalytic flow oxygenation of phenols .

Huber, A. (2024) Chiral recognition on molecular nanowires from square planar platinum(II) complexes .

Hugo, M. (2024) Synthesis towards spherical molecules.

Jakobi, M. (2024) Synthesis and diversification of nitrogen and silicon heterocycles used as organic fluorophores .

Reznikova, K. (2024) Tailor-made structures for molecular junctions: from linear wires to molecular loops.

Moser, D., Schmidt, T.A. and Sparr, C. (2023) ‘Diastereodivergent Catalysis’, JACS Au, 3(10), pp. 2612–2630. Available at: https://doi.org/10.1021/jacsau.3c00216.

Moser, D., Jana, K. and Sparr, C. (2023) ‘Atroposelective PIII/PV=O Redox Catalysis for the Isoquinoline-Forming Staudinger–aza-Wittig Reaction’, Angewandte Chemie - International Edition, 62(39). Available at: https://doi.org/10.1002/anie.202309053.

Moser, D., Jana, K. and Sparr, C. (2023) ‘Atroposelective PIII/PV=O Redox Catalysis for the Isoquinoline-Forming Staudinger–aza-Wittig Reaction’, Angewandte Chemie. 14.07.2023, 135(39). Available at: https://doi.org/10.1002/ange.202309053.

Moser, Daniel (2023) Diastereodivergent arene-forming aldol condensations and atroposelective pyridoannelations. Doctoral Thesis. University of Basel.

Schmidt, T.A. et al. (2023) ‘Catalyst Control over Threefold Stereogenicity: Selective Synthesis of Atropisomeric Sulfones with Stereogenic C−S Axes’, Angewandte Chemie - International Edition, 62(21). Available at: https://doi.org/10.1002/anie.202302084.

Schmidt, T.A. et al. (2023) ‘Katalysatorkontrolle über dreifache Stereogenität: Selektive Synthese atropisomerer Sulfone mit stereogenen C−S-Achsen’, Angewandte Chemie. 14.03.2023, 135(21). Available at: https://doi.org/10.1002/ange.202302084.

Miladinov, D. (2023) Toward Divergent Compound Library Synthesis by Cascaded, Heterogeneous Catalysis in Continuous-Flow Microfluidic Reactors.

Schmidt, T. (2023) Catalyst control over three- and fourfold stereogenicity.

Vogel, C.H. (2023) Repurposing MGMT as a kill switch in chemical biology and as a novel mode of action in protein degradation.

Jončev, Z. and Sparr, C. (2022) ‘Atroposelective Arene-Forming Alkene Metathesis**’, Angewandte Chemie. 25.10.2022, 134(51). Available at: https://doi.org/10.1002/ange.202211168.

Dong, J., Ostertag, A. and Sparr, C. (2022) ‘o-Quinodimethane Atropisomers: Enantioselective Synthesis and Stereospecific Transformation’, Angewandte Chemie. 18.10.2022, 134(50). Available at: https://doi.org/10.1002/ange.202212627.

Hutskalova, V. and Sparr, C. (2022) ‘Control over Stereogenic N-N Axes by Pd-Catalyzed 5- endo -Hydroaminocyclizations’, Synthesis (Germany), 55(11), pp. 1770–1782. Available at: https://doi.org/10.1055/a-1993-6899.

Moser, D. and Sparr, C. (2022) ‘Synthesis of Atropisomeric Two-Axis Systems by the Catalyst-Controlled syn- and anti-Selective Arene-Forming Aldol Condensation’, Angewandte Chemie. 27.03.2022, 134(24). Available at: https://doi.org/10.1002/ange.202202548.

Jončev, Zlatko and Sparr, Christof (2022) ‘Atroposelective arene-forming alkene metathesis’, ChemRxiv [Preprint]. Cambridge University Press (ChemRxiv). Available at: https://doi.org/10.26434/chemrxiv-2022-w8h26.

Wu, X. and Sparr, C. (2022) ‘Stereoselective Synthesis of Atropisomeric Acridinium Salts by the Catalyst-Controlled Cyclization of ortho-Quinone Methide Iminiums’, Angewandte Chemie. 15.02.2022, 134(19). Available at: https://doi.org/10.1002/ange.202201424.

Boris, L. (2022) Extending artificial metalloenzymes for the uncaging of drugs on cells.

Dong, Jianyang, Ostertag, Andreas and Sparr, Christof (2022) ‘o-Quinodimethane Atropisomers: Enantioselective Synthesis and Stereospecific Transformation’, Angewandte Chemie International Edition, 61(50), p. e202212627. Available at: https://doi.org/10.1002/anie.202212627.

Hutskalova, Valeriia and Sparr, Christof (2022) ‘The Versatility of the Aryne-Imine-Aryne Coupling for the Synthesis of Acridinium Photocatalysts’, Synlett, 33(12), pp. 1180–1183. Available at: https://doi.org/10.1055/s-0040-1720349.

Hutskalova, V. and Sparr, C. (2022) ‘Synthesis and Applications of Acridinium Salts (Update 2022)’, in Science of Synthesis. Georg Thieme Verlag (Science of Synthesis), pp. 1–44. Available at: https://doi.org/10.1055/sos-SD-115-00850.

Jakobi, Markus and Sparr, Christof (2022) ‘Streamlined Synthesis of Aminoacridinium Photocatalysts with Improved Photostability’, Organic process research & development, 26(9), pp. 2756–2760. Available at: https://doi.org/10.1021/acs.oprd.2c00209.

Jakobi, Markus, Zilate, Bouthayna and Sparr, Christof (2022) ‘Synthesis of Diarylaminoacridinium Photocatalysts by Halogen-Metal Exchange Combined with Directed ortho Metalations’, Advanced Synthesis and Catalysis, 364(19), pp. 3384–3388. Available at: https://doi.org/10.1002/adsc.202200819.

Jončev, Z. (2022) Atroposelective Arene-Forming Alkene Metathesis using Small Molecule Catalysts and Artificial Metalloenzymes.

Jončev, Zlatko and Sparr, Christof (2022) ‘Atroposelective Arene-Forming Alkene Metathesis’, Angewandte Chemie International Edition, 61(51), p. e202211168. Available at: https://doi.org/10.1002/anie.202211168.

Moser, Daniel and Sparr, Christof (2022) ‘Synthesis of Atropisomeric Two-Axis Systems by the Catalyst-Controlled syn- and anti-Selective Arene-Forming Aldol Condensation’, Angewandte Chemie International Edition, 61(24), p. e202202548. Available at: https://doi.org/10.1002/anie.202202548.

Schmidt, Tanno A. and Sparr, Christof (2022) ‘Photocatalytic deracemisation of cobalt(III) complexes with fourfold stereogenicity’, Chemical Communications, 58(87), pp. 12172–12175. Available at: https://doi.org/10.1039/d2cc05196f.

Wu, Xingxing et al. (2022) ‘X-Ray Crystallographic Studies of Quasi-Racemates for Absolute Configuration Determinations’, Helvetica Chimica Acta, 105(11), p. e202200117. Available at: https://doi.org/10.1002/hlca.202200117.

Wu, Xingxing and Sparr, Christof (2022) ‘Stereoselective Synthesis of Atropisomeric Acridinium Salts by the Catalyst-Controlled Cyclization of ortho-Quinone Methide Iminiums’, Angewandte Chemie International Edition, 61(19), p. e202201424. Available at: https://doi.org/10.1002/anie.202201424.

Wu, Xingxing and Sparr, Christof (2022) ‘Retrosynthetic polyketide disconnections for unnatural aromatics’, Trends in chemistry, 4(5), pp. 367–370. Available at: https://doi.org/10.1016/j.trechm.2022.01.013.

Hutskalova, Valeriia and Sparr, Christof (2022) ‘Synthesis and Applications of Acridinium Salts (Chapter 15.9.4)’, in Donohoe, Timothy J.; Krause, Norbert; Marsden, Stephen Philip; Montchamp, Jean-Luc; Terentev, Alexander; Weinreb, Steven M. (ed.) Science of Synthesis: Knowledge Updates. Stuttgart: Thieme (Science of Synthesis: Knowledge Updates), pp. 1–44.

Schmidt, T.A. and Sparr, C. (2021) ‘Katalysatorkontrollierte stereoselektive Barton‐Kellogg‐Olefinierung’, Angewandte Chemie. 20.08.2021, 133(44), pp. 24105–24111. Available at: https://doi.org/10.1002/ange.202109519.

Scherrer, D. et al. (2021) ‘Reaktionsverfolgung von Festphasensynthesen in selbstassemblierenden Monolagen mit oberflächenverstärkter Raman‐Spektroskopie’, Angewandte Chemie. 28.05.2021, 133(33), pp. 18126–18134. Available at: https://doi.org/10.1002/ange.202102319.

Wu, X. et al. (2021) ‘Publisher Correction: Catalyst control over sixfold stereogenicity (Nature Catalysis, (2021), 4, 6, (457-462), 10.1038/s41929-021-00615-z)’, Nature Catalysis, 4(6). Available at: https://doi.org/10.1038/s41929-021-00645-7.

Bonrath, W. et al. (2021) ‘New Transition Metal Catalyst’.

Bonrath, W. et al. (2021) ‘Photooxidation of 2,3,5-Trimethylphenol’.

Bonrath, W. et al. (2021) ‘Photooxidation of 2,3,6-Trimethylphenol’.

Castrogiovanni, A. (2021) Catalytic Stereodivergent Synthesis of Atropisomeric Multiaxis Systems and their Application in Electron Transfer Studies and Ligand Design.

Hutskalova, Valeriia, Prescimone, Alessandro and Sparr, Christof (2021) ‘Synthesis of Helical and Planar Extended-Phenanthridinium Salts’, Helvetica Chimica Acta, 104(12), p. e2100182. Available at: https://doi.org/10.1002/hlca.202100182.

Hutskalova, Valeriia and Sparr, Christof (2021) ‘Ad Hoc Adjustment of Photoredox Properties by the Late-Stage Diversification of Acridinium Photocatalysts’, Organic letters, 23(13), pp. 5143–5147. Available at: https://doi.org/10.1021/acs.orglett.1c01673.

Raps, F.C. (2021) Catalyst Controlled Divergent Transannular Polyketide Cyclizations and Selective Preparation of Stereoisomers with Threefold Stereogenicity.

Scherrer, D. (2021) Silicon-based Plasmonic Surfaces and Flow Microreactors.

Schmidt, Tanno A. and Sparr, Christof (2021) ‘Catalyst-Controlled Stereoselective Barton-Kellogg Olefination’, Angewandte Chemie International Edition, 60(44), pp. 23911–23916. Available at: https://doi.org/10.1002/anie.202109519.

Schmidt, Tanno A. and Sparr, Christof (2021) ‘Catalyst Control over Twofold and Higher-Order Stereogenicity by Atroposelective Arene Formation’, Accounts of Chemical Research, 54(12), pp. 2764–2774. Available at: https://doi.org/10.1021/acs.accounts.1c00178.

Triandafillidi, Ierasia et al. (2021) ‘Aldehyde-catalyzed epoxidation of unactivated alkenes with aqueous hydrogen peroxide’, Chemical Science, 12(30), pp. 10191–10196. Available at: https://doi.org/10.1039/d1sc02360h.

Wellauer, Joel et al. (2021) ‘Organophotocatalytic Aerobic Oxygenation of Phenols in a Visible-Light Continuous-Flow Photoreactor’, Chemistry - A European Journal, 27(38), pp. 9748–9752. Available at: https://doi.org/10.1002/chem.202101313.

Wu, Xingxing et al. (2021) ‘Catalyst control over sixfold stereogenicity’, Nature Catalysis, 4(6), pp. 457–462. Available at: https://doi.org/10.1038/s41929-021-00615-z.

Raps, F.C. et al. (2020) ‘Catalyst‐Controlled Transannular Polyketide Cyclization Cascades: Selective Folding of Macrocyclic Polyketides’, Angewandte Chemie. 14.07.2020, 132(42), pp. 18548–18552. Available at: https://doi.org/10.1002/ange.202005733.

Fäseke, Vincent C., Raps, Felix C. and Sparr, Christof (2020) ‘Polyketide Cyclizations for the Synthesis of Polyaromatics’, Angewandte Chemie. 03.12.2019, 132(18), pp. 7039–7047. Available at: https://doi.org/10.1002/ange.201911255.

Bourgeois, Frederic et al. (2020) ‘Catalyst Repurposing Sequential Catalysis by Harnessing Regenerated Prolinamide Organocatalysts as Transfer Hydrogenation Ligands’, Organic Letters, 22(1), pp. 110–115. Available at: https://doi.org/10.1021/acs.orglett.9b04033.

Castrogiovanni, Alessandro et al. (2020) ‘JoyaPhos: An Atropisomeric Teraryl Monophosphine Ligand’, Chemistry - A European Journal, 26(44), pp. 9864–9868. Available at: https://doi.org/10.1002/chem.202001269.

Fäseke, Vincent C., Raps, Felix C. and Sparr, Christof (2020) ‘Polyketide Cyclizations for the Synthesis of Polyaromatics’, Angewandte Chemie (International ed. in English), 59(18), pp. 6975–6983. Available at: https://doi.org/10.1002/anie.201911255.

Fischer, Christian et al. (2020) ‘Modulation of Acridinium Organophotoredox Catalysts Guided by Photophysical Studies’, ACS Catalysis, 10(1), pp. 210–215. Available at: https://doi.org/10.1021/acscatal.9b03606.

Moser, Daniel et al. (2020) ‘Catalytic Cascade Reactions Inspired by Polyketide Biosynthesis’, Chimia, 74(9), pp. 699–703. Available at: https://doi.org/10.2533/chimia.2020.699.

Raps, Felix C. et al. (2020) ‘Catalyst-Controlled Transannular Polyketide Cyclization Cascades: Selective Folding of Macrocyclic Polyketides’, Angewandte Chemie International Edition, 59(42), pp. 18390–18394. Available at: https://doi.org/10.1002/anie.202005733.

Witzig, Reto M. and Sparr, Christof (2020) ‘Synthesis of Enantioenriched Tetra-ortho-3,3′-substituted Biaryls by Small-Molecule-Catalyzed Noncanonical Polyketide Cyclizations’, Synlett, 31(1), pp. 13–20. Available at: https://doi.org/10.1055/s-0039-1690215.

Wu, Xingxing et al. (2020) ‘Catalyst-Control over Sixfold Stereogenicity’, ChemRxiv [Preprint]. Cambridge University Press (ChemRxiv). Available at: https://doi.org/10.26434/chemrxiv.12213362.v1.

Zilate, B. (2020) Study of rotationally restricted systems and synthesis of acridinium photocatalysts. Available at: https://doi.org/10.5451/unibas-007229180.

Zilate, Bouthayna, Fischer, Christian and Sparr, Christof (2020) ‘Design and application of aminoacridinium organophotoredox catalysts’, Chemical Communications, 56(12), pp. 1767–1775. Available at: https://doi.org/10.1039/c9cc08524f.

Bannwart, L.M. (2019) From Structural Beauty to Chemical Fragility: Diacetylene Bridged “Geländer” Oligomers.

Castrogiovanni, Alessandro et al. (2019) ‘Shortcuts for Electron-Transfer through the Secondary Structure of Helical Oligo-1,2-Naphthylenes’, Chemistry - A European Journal, 25, pp. 16748–16754. Available at: https://doi.org/10.1002/chem.201904771.

Fäseke, V.C. (2019) Atroposelective and transannular catalyst-controlled polyketide cyclizations. Available at: https://doi.org/10.5451/unibas-007133783.

Jakobi, Markus et al. (2019) ‘A General Protocol for Robust Sonogashira Reactions in Micellar Medium’, Helvetica Chimica Acta, 102(3), p. e1900024. Available at: https://doi.org/10.1002/hlca.201900024.

Kaldre, Dainis et al. (2019) ‘Interface-rich Aqueous Systems for Sustainable Chemical Synthesis’, Chimia, 73(9), pp. 714–719. Available at: https://doi.org/10.2533/chimia.2019.714.

Lotter, D. (2019) Stereodivergent synthesis of oligo-1,2-naphthylenes and studies towards the total synthesis of naphthacemycin B1. Available at: https://doi.org/10.5451/unibas-007133630.

Sparr, Christof (2019) ‘Author Profile’, Angewandte Chemie International Edition, 58, p. 944. Available at: https://doi.org/10.1002/anie.201809582.

Witzig, R.M. (2019) Noncanonical polyketide cyclization and stereoselective synthesis of configurationally stable Csp2-Csp3 atropisomers. Available at: https://doi.org/10.5451/unibas-007155438.

Witzig, Reto M. et al. (2019) ‘Atroposelective synthesis of tetra-ortho-substituted biaryls by catalyst-controlled non-canonical polyketide cyclizations’, Nature Catalysis, 2(10), pp. 925–930. Available at: https://doi.org/10.1038/s41929-019-0345-0.

Zilate, Bouthayna et al. (2019) ‘Scalable Synthesis of Acridinium Catalysts for Photoredox Deuterations’, Synthesis, 51(23), pp. 4359–4365. Available at: https://doi.org/10.1055/s-0039-1690694.

Fischer, C. (2018) Direct synthesis of arenes and heterocycles from esters and their use as organophotocatalysts. Available at: https://doi.org/10.5451/unibas-007229909.

Fischer, Christian and Sparr, Christof (2018) ‘Direct Transformation of Esters into Heterocyclic Fluorophores’, Angewandte Chemie International Edition, 57(9), pp. 2436–2440. Available at: https://doi.org/10.1002/anie.201711296.

Fischer, Christian and Sparr, Christof (2018) ‘Synthesis of 1,5-Bifunctional Organolithium Reagents by Double Directed ortho-Metalation: Direct Transformation of Esters into 1,8-Dimethoxy-Acridinium Salts’, Tetrahedron, 74(38), pp. 5486–5493. Available at: https://doi.org/10.1016/j.tet.2018.04.060.

Fischer, Christian and Sparr, Christof (2018) ‘Configurationally Stable Atropisomeric Acridinium Fluorophores’, Synlett, 29(16), pp. 2176–2180. Available at: https://doi.org/10.1055/s-0037-1610233.

Grogg, Marcel et al. (2018) ‘Cell penetration, herbicidal activity, and in-vivo-toxicity of oligo-arginine derivatives and of novel guanidinium-rich compounds derived from the biopolymer cyanophycin’, Helvetica Chimica Acta, 101(10), p. e1800112. Available at: https://doi.org/10.1002/hlca.201800112.

Link, A. (2018) 1,5-bifunctional organomagnesium reagents for the direct transformation of esters into arenes. Available at: https://doi.org/10.5451/unibas-006812184.

Link, Achim and Sparr, Christof (2018) ‘Stereoselective Arene-Formation (Review)’, Chemical Society Reviews, 47(11), pp. 3804–3815. Available at: https://doi.org/10.1039/c7cs00875a.

Link, Achim and Sparr, Christof (2018) ‘Remote Central-to-Axial Chirality Conversion: Direct Atroposelective Ester to Biaryl Transformation’, Angewandte Chemie International Edition, 57(24), pp. 7136–7139. Available at: https://doi.org/10.1002/anie.201803472.

Lotter, Dominik et al. (2018) ‘Catalyst-Controlled Stereodivergent Synthesis of Atropisomeric Multi-Axis Systems’, ACS Central Science, 4(5), pp. 656–660. Available at: https://doi.org/10.1021/acscentsci.8b00204.

Lotter, Dominik and Sparr, Christof (2018) ‘Diaryl Magnesium Lithium Alkoxides Derived from (Z)‐4‐(2‐Bromophenyl)but‐3‐en‐1‐ol’, Encyclopedia of Reagents for Organic Synthesis [Preprint]. Available at: https://doi.org/10.1002/047084289x.rn02170.

Zilate, Bouthayna, Castrogiovanni, Alessandro and Sparr, Christof (2018) ‘Catalyst-Controlled Stereoselective Synthesis of Atropisomers (Perspective)’, ACS Catalysis, 8(4), pp. 2981–2988. Available at: https://doi.org/10.1021/acscatal.7b04337.

Fäseke, Vincent C. et al. (2017) ‘Catalytic Arene-forming Aldol Condensation: Stereoselective Synthesis of Rotationally Restricted Aromatic Compounds’, Chimia, 71(9), pp. 596–599. Available at: https://doi.org/10.2533/chimia.2017.596.

Link, Achim, Fischer, Christian and Sparr, Christof (2017) ‘A 1,5-Bifunctional Organomagnesium Reagent for the Synthesis of Disubstituted Anthracenes and Anthrones’, Synthesis, 49(2), pp. 397–402. Available at: https://doi.org/10.1055/s-0036-1588087.

Witzig, Reto M. et al. (2017) ‘Stereoselective Arene-Forming Aldol Condensation: Catalyst-Controlled Synthesis of Axially Chiral Compounds’, Chemistry - A European Journal, 23(53), pp. 12960–12966. Available at: https://doi.org/10.1002/chem.201702471.

Braeuer, Thomas M., Zhang, Qi and Tiefenbacher, Konrad (2016) ‘Iminium Catalysis inside a Self-Assembled Supramolecular Capsule: Modulation of Enantiomeric Excess’, Angewandte Chemie International Edition, 55(27), pp. 7698–701. Available at: https://doi.org/10.1002/anie.201602382.

Catti, Lorenzo, Zhang, Qi and Tiefenbacher, Konrad (2016) ‘Advantages of Catalysis in Self-Assembled Molecular Capsules’, Chemistry - A European Journal, 22(27), pp. 9060–6. Available at: https://doi.org/10.1002/chem.201600726.

Fäseke, Vincent C. and Sparr, Christof (2016) ‘Stereoselective Arene-Forming Aldol Condensation: Synthesis of Axially Chiral Aromatic Amides’, Angewandte Chemie International Edition, 55(25), pp. 7261–4. Available at: https://doi.org/10.1002/anie.201602689.

Lotter, Dominik et al. (2016) ‘Stereoselective Arene-Forming Aldol Condensation: Synthesis of Configurationally Stable Oligo-1,2-naphthylenes’, Angewandte Chemie International Edition, 55(8), pp. 2920–2923. Available at: https://doi.org/10.1002/anie.201510259.

Thamm, Irene et al. (2016) ‘A six-step total synthesis of α-thujone and d6-α-thujone, enabling facile access to isotopically labelled metabolites’, Chemical Communications, 52(78), pp. 11701–11703. Available at: https://doi.org/10.1039/c6cc05376a.

Link, Achim, Fischer, Christian and Sparr, Christof (2015) ‘Direct Transformation of Esters into Arenes with 1,5-Bifunctional Organo­magnesium Reagents’, Angewandte Chemie International Edition, 54(41), pp. 12163–12166. Available at: https://doi.org/10.1002/anie.201505414.