{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,26]],"date-time":"2026-09-26T16:00:26Z","timestamp":1790438426658,"version":"4.1.0"},"reference-count":56,"publisher":"Wiley","license":[{"start":{"date-parts":[[2026,9,26]],"date-time":"2026-09-26T00:00:00Z","timestamp":1790380800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,9,26]],"date-time":"2026-09-26T00:00:00Z","timestamp":1790380800000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"funder":[{"DOI":"10.13039\/100005156","name":"Alexander von Humboldt-Stiftung","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100005156","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000001","name":"National Science Foundation","doi-asserted-by":"publisher","award":["CHE\u20102338438"],"award-info":[{"award-number":["CHE\u20102338438"]}],"id":[{"id":"10.13039\/100000001","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Angew Chem Int Ed"],"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>\n                    Strained bicyclo[1.1.0]butanes (BCBs) have emerged as versatile precursors for accessing highly reactive intermediates, enabling unconventional bond constructions through strain\u2010release pathways. Herein, we report a cobalt(II)\u2010catalyzed strategy that combines thermal activation of BCBs with selective radical capture by Co(II) to afford head\u2010to\u2010head fused bicyclo[2.1.1]hexanes (BCHex). We propose that thermal activation of the BCB generates a reactive diradical intermediate, which is intercepted by a tailored bidentate phosphine Co(II) cationic complex via oxidative radical coupling, followed by a [2\u03c3+2\u03c0] cycloaddition with indoles. Mechanistic investigations, including\n                    <jats:sup>31<\/jats:sup>\n                    P NMR spectroscopy, cyclic voltammetry, electron paramagnetic resonance (EPR), and density functional theory (DFT) studies, provide insights into the plausible reaction pathway. The involvement of paramagnetic Co(II) species is consistent with the broad features observed in both EPR and nuclear magnetic resonance (NMR) spectra of the catalyst. In addition, four structurally distinct Co(II) complexes were synthesized, fully characterized by UV\u2013Vis and Fourier\u2010transform infrared (FTIR) spectroscopy, and evaluated as catalysts for the transformation. The cationic nature of the Co(II) species was further confirmed by phosphine oxide trapping experiments and single\u2010crystal X\u2010ray crystallography.\n                  <\/jats:p>","DOI":"10.1002\/anie.8666577","type":"journal-article","created":{"date-parts":[[2026,9,26]],"date-time":"2026-09-26T15:27:49Z","timestamp":1790436469000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Cobalt\u2010Catalyzed [2\u03c3+2\u03c0] Cycloaddition via Site\u2010Selective Capture of Bicyclobutane Diradical"],"prefix":"10.1002","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6875-689X","authenticated-orcid":false,"given":"Tanmayee","family":"Nanda","sequence":"first","affiliation":[{"name":"Institute of Organic Chemistry Albert\u2010Ludwigs\u2010University of Freiburg Freiburg Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7800-5950","authenticated-orcid":false,"given":"Alexander","family":"Umanzor","sequence":"additional","affiliation":[{"name":"Department of Chemistry and Biochemistry Oberlin College  Oberlin Ohio USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Julia","family":"Gartzke","sequence":"additional","affiliation":[{"name":"Institute of Organic Chemistry Albert\u2010Ludwigs\u2010University of Freiburg Freiburg Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-6337-2155","authenticated-orcid":false,"given":"Jeremy T.","family":"Maddigan\u2010Wyatt","sequence":"additional","affiliation":[{"name":"Institute of Organic Chemistry Albert\u2010Ludwigs\u2010University of Freiburg Freiburg Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0000-9364-7951","authenticated-orcid":false,"given":"Philipp","family":"Thielert","sequence":"additional","affiliation":[{"name":"Institute of Physical Chemistry Albert\u2010Ludwigs\u2010University of Freiburg  Freiburg Germany"},{"name":"Institute of Physical Chemistry II University of Ulm  Ulm Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4090-7435","authenticated-orcid":false,"given":"Stefan","family":"Weber","sequence":"additional","affiliation":[{"name":"Institute of Physical Chemistry Albert\u2010Ludwigs\u2010University of Freiburg  Freiburg Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2990-974X","authenticated-orcid":false,"given":"Sabine","family":"Richert","sequence":"additional","affiliation":[{"name":"Institute of Physical Chemistry Albert\u2010Ludwigs\u2010University of Freiburg  Freiburg Germany"},{"name":"Institute of Physical Chemistry II University of Ulm  Ulm Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shuming","family":"Chen","sequence":"additional","affiliation":[{"name":"Department of Chemistry and Biochemistry Oberlin College  Oberlin Ohio USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3973-2212","authenticated-orcid":false,"given":"Daniel B.","family":"Werz","sequence":"additional","affiliation":[{"name":"Institute of Organic Chemistry Albert\u2010Ludwigs\u2010University of Freiburg Freiburg Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,9,26]]},"reference":[{"key":"e_1_2_8_2_1","doi-asserted-by":"publisher","DOI":"10.1021\/jm901241e"},{"key":"e_1_2_8_3_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.drudis.2022.05.021"},{"key":"e_1_2_8_4_1","doi-asserted-by":"publisher","DOI":"10.1021\/ar500437h"},{"key":"e_1_2_8_5_1","doi-asserted-by":"publisher","DOI":"10.1039\/D2SC03948F"},{"key":"e_1_2_8_6_1","doi-asserted-by":"publisher","DOI":"10.1021\/jacs.3c08206"},{"key":"e_1_2_8_7_1","doi-asserted-by":"publisher","DOI":"10.1038\/s42004\u2010022\u201000811\u20103"},{"key":"e_1_2_8_8_1","doi-asserted-by":"publisher","DOI":"10.31635\/ccschem.025.202505825"},{"key":"e_1_2_8_9_1","doi-asserted-by":"publisher","DOI":"10.1021\/ja00456a040"},{"key":"e_1_2_8_10_1","doi-asserted-by":"publisher","DOI":"10.1002\/anie.198505881"},{"key":"e_1_2_8_11_1","doi-asserted-by":"publisher","DOI":"10.1021\/cr010016n"},{"key":"e_1_2_8_12_1","doi-asserted-by":"publisher","DOI":"10.1039\/C3CS60238A"},{"key":"e_1_2_8_13_1","doi-asserted-by":"publisher","DOI":"10.1002\/anie.201309886"},{"key":"e_1_2_8_14_1","doi-asserted-by":"publisher","DOI":"10.1002\/anie.201909213"},{"key":"e_1_2_8_15_1","doi-asserted-by":"publisher","DOI":"10.1002\/adsc.201901332"},{"key":"e_1_2_8_16_1","doi-asserted-by":"publisher","DOI":"10.1002\/9783527835652"},{"key":"e_1_2_8_17_1","doi-asserted-by":"publisher","DOI":"10.1038\/s41557\u2010023\u201001135\u2010y"},{"key":"e_1_2_8_18_1","doi-asserted-by":"publisher","DOI":"10.1021\/acs.orglett.3c03222"},{"key":"e_1_2_8_19_1","doi-asserted-by":"publisher","DOI":"10.1002\/anie.202304771"},{"key":"e_1_2_8_20_1","doi-asserted-by":"publisher","DOI":"10.1039\/D4SC02767A"},{"key":"e_1_2_8_21_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.tchem.2024.100070"},{"key":"e_1_2_8_22_1","doi-asserted-by":"publisher","DOI":"10.1039\/D4QO01741B"},{"key":"e_1_2_8_23_1","doi-asserted-by":"publisher","DOI":"10.1002\/chem.202404099"},{"key":"e_1_2_8_24_1","doi-asserted-by":"publisher","DOI":"10.1021\/acs.orglett.5c02160"},{"key":"e_1_2_8_25_1","doi-asserted-by":"publisher","DOI":"10.1021\/jacsau.4c00839"},{"key":"e_1_2_8_26_1","doi-asserted-by":"publisher","DOI":"10.1021\/ja00955a021"},{"key":"e_1_2_8_27_1","doi-asserted-by":"publisher","DOI":"10.1021\/jacs.2c02976"},{"key":"e_1_2_8_28_1","doi-asserted-by":"publisher","DOI":"10.1021\/ja00513a054"},{"key":"e_1_2_8_29_1","doi-asserted-by":"publisher","DOI":"10.1021\/ja00499a057"},{"key":"e_1_2_8_30_1","doi-asserted-by":"publisher","DOI":"10.1021\/jacs.4c04403"},{"key":"e_1_2_8_31_1","doi-asserted-by":"publisher","DOI":"10.1021\/acscatal.4c05067"},{"key":"e_1_2_8_32_1","doi-asserted-by":"publisher","DOI":"10.1021\/acs.orglett.5c05325"},{"key":"e_1_2_8_33_1","doi-asserted-by":"publisher","DOI":"10.1021\/jacsau.5c00341"},{"key":"e_1_2_8_34_1","doi-asserted-by":"publisher","DOI":"10.1038\/s41467\u2010024\u201048494\u20109"},{"key":"e_1_2_8_35_1","doi-asserted-by":"publisher","DOI":"10.1039\/D5SC02836A"},{"key":"e_1_2_8_36_1","doi-asserted-by":"publisher","DOI":"10.1021\/jacs.4c10968"},{"key":"e_1_2_8_37_1","doi-asserted-by":"publisher","DOI":"10.1021\/jacs.0c00245"},{"key":"e_1_2_8_38_1","doi-asserted-by":"publisher","DOI":"10.1039\/D5QO00020C"},{"key":"e_1_2_8_39_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.xcrp.2024.102346"},{"key":"e_1_2_8_40_1","doi-asserted-by":"publisher","DOI":"10.1002\/anie.202310066"},{"key":"e_1_2_8_41_1","doi-asserted-by":"publisher","DOI":"10.1002\/anie.202308606"},{"key":"e_1_2_8_42_1","doi-asserted-by":"publisher","DOI":"10.1038\/s41586\u2010025\u201008745\u20101"},{"key":"e_1_2_8_43_1","doi-asserted-by":"publisher","DOI":"10.1021\/jacs.5b01197"},{"key":"e_1_2_8_44_1","doi-asserted-by":"publisher","DOI":"10.1002\/9783527621545.ch1"},{"key":"e_1_2_8_45_1","unstructured":"\u201cDeposition numbers 2476072 (for compound 3aa) and 2531641 (for compound Co\u2010C2a) contain the supplementary crystallographic data for this paper. These data are provided free of charge by the joint Cambridge crystallographic data centre and fachinformationszentrum karlsruhe access structures service \u201d."},{"key":"e_1_2_8_46_1","doi-asserted-by":"publisher","DOI":"10.1021\/jacs.2c08865"},{"key":"e_1_2_8_47_1","doi-asserted-by":"publisher","DOI":"10.1021\/acs.inorgchem.3c04491"},{"key":"e_1_2_8_48_1","doi-asserted-by":"publisher","DOI":"10.1021\/jacs.3c04866"},{"key":"e_1_2_8_49_1","doi-asserted-by":"publisher","DOI":"10.1021\/ja026433e"},{"key":"e_1_2_8_50_1","doi-asserted-by":"publisher","DOI":"10.1021\/acs.inorgchem.0c01191"},{"key":"e_1_2_8_51_1","doi-asserted-by":"publisher","DOI":"10.1021\/ic400980b"},{"key":"e_1_2_8_52_1","doi-asserted-by":"publisher","DOI":"10.1021\/ic00225a008"},{"key":"e_1_2_8_53_1","doi-asserted-by":"publisher","DOI":"10.1021\/acscatal.5c07125"},{"key":"e_1_2_8_54_1","doi-asserted-by":"publisher","DOI":"10.1038\/s41570\u2010022\u201000447\u2010w"},{"key":"e_1_2_8_55_1","doi-asserted-by":"publisher","DOI":"10.1021\/acscatal.5c00303"},{"key":"e_1_2_8_56_1","doi-asserted-by":"publisher","DOI":"10.1039\/d6sc01258b"},{"key":"e_1_2_8_57_1","unstructured":"While both Quartet and Doublet Spin States Were Computationally Evaluated for the Co\u2010containing Structures the Quartet state Was Found to be Consistently More Favorable by >20 kcal\/mol."}],"container-title":["Angewandte Chemie International Edition"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/anie.8666577","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/full-xml\/10.1002\/anie.8666577","content-type":"application\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/anie.8666577","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,26]],"date-time":"2026-09-26T15:27:52Z","timestamp":1790436472000},"score":1,"resource":{"primary":{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/10.1002\/anie.8666577"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9,26]]},"references-count":56,"alternative-id":["10.1002\/anie.8666577"],"URL":"https:\/\/doi.org\/10.1002\/anie.8666577","archive":["Portico"],"relation":{},"ISSN":["1433-7851","1521-3773"],"issn-type":[{"value":"1433-7851","type":"print"},{"value":"1521-3773","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,26]]},"assertion":[{"value":"2026-05-04","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-09-16","order":2,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-09-26","order":3,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}],"article-number":"e8666577"}}