{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,8]],"date-time":"2026-10-08T00:28:30Z","timestamp":1791419310563,"version":"4.3.3"},"reference-count":108,"publisher":"Wiley","issue":"45","license":[{"start":{"date-parts":[[2022,10,11]],"date-time":"2022-10-11T00:00:00Z","timestamp":1665446400000},"content-version":"am","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"},{"start":{"date-parts":[[2022,10,11]],"date-time":"2022-10-11T00:00:00Z","timestamp":1665446400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000001","name":"National Science Foundation","doi-asserted-by":"publisher","award":["CHE-1339674"],"award-info":[{"award-number":["CHE-1339674"]}],"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"],"published-print":{"date-parts":[[2022,11,7]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>A direct dearomative photocatalyzed (3+2) cycloaddition between indoles and vinyldiazo reagents is described. The transformation is enabled by the development of a novel oxidizing Cr<jats:sup>III<\/jats:sup> photocatalyst, its specific reactivity attributed to increased absorptive properties over earlier Cr analogs and greater stability than Ru counterparts. A variety of fused indoline compounds are synthesized using this method, including densely functionalized ring systems that are feasible due to base\u2010free conditions. Experimental insights corroborate a cycloaddition initiated by nucleophilic attack at C3 of the indole radical cation by the vinyldiazo species.<\/jats:p>","DOI":"10.1002\/anie.202212187","type":"journal-article","created":{"date-parts":[[2022,9,5]],"date-time":"2022-09-05T16:59:43Z","timestamp":1662397183000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":47,"title":["Dearomative (3+2) Cycloadditions between Indoles and Vinyldiazo Species Enabled by a Red\u2010Shifted Chromium Photocatalyst"],"prefix":"10.1002","volume":"61","author":[{"given":"Bradley K.","family":"Gall","sequence":"first","affiliation":[{"name":"Department of Chemistry University of Georgia  Athens GA 30602 USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Avery K.","family":"Smith","sequence":"additional","affiliation":[{"name":"Department of Chemistry University of Georgia  Athens GA 30602 USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9412-0713","authenticated-orcid":false,"given":"Eric M.","family":"Ferreira","sequence":"additional","affiliation":[{"name":"Department of Chemistry University of Georgia  Athens GA 30602 USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2022,10,11]]},"reference":[{"key":"e_1_2_7_1_1","unstructured":"For select reviews and perspectives see:"},{"key":"e_1_2_7_2_2","doi-asserted-by":"publisher","DOI":"10.1039\/B913880N"},{"key":"e_1_2_7_3_2","doi-asserted-by":"publisher","DOI":"10.1021\/cr300503r"},{"key":"e_1_2_7_4_2","doi-asserted-by":"publisher","DOI":"10.1021\/cs400088e"},{"key":"e_1_2_7_5_2","doi-asserted-by":"publisher","DOI":"10.1039\/C5OB01349F"},{"key":"e_1_2_7_6_2","doi-asserted-by":"publisher","DOI":"10.1021\/acs.chemrev.6b00057"},{"key":"e_1_2_7_7_2","doi-asserted-by":"publisher","DOI":"10.1021\/acs.joc.6b01449"},{"key":"e_1_2_7_8_2","doi-asserted-by":"publisher","DOI":"10.1039\/D1CS00311A"},{"key":"e_1_2_7_9_1","unstructured":"\u00a0"},{"key":"e_1_2_7_10_2","doi-asserted-by":"publisher","DOI":"10.1002\/anie.201501220"},{"key":"e_1_2_7_10_3","doi-asserted-by":"publisher","DOI":"10.1002\/ange.201501220"},{"key":"e_1_2_7_11_2","doi-asserted-by":"publisher","DOI":"10.1021\/jacs.6b02723"},{"key":"e_1_2_7_12_2","doi-asserted-by":"publisher","DOI":"10.1039\/C6SC03303B"},{"key":"e_1_2_7_13_2","doi-asserted-by":"publisher","DOI":"10.1021\/acs.orglett.7b01095"},{"key":"e_1_2_7_14_2","doi-asserted-by":"publisher","DOI":"10.1021\/acscatal.8b03013"},{"key":"e_1_2_7_15_2","doi-asserted-by":"publisher","DOI":"10.1002\/anie.201805732"},{"key":"e_1_2_7_15_3","doi-asserted-by":"publisher","DOI":"10.1002\/ange.201805732"},{"key":"e_1_2_7_16_1","doi-asserted-by":"publisher","DOI":"10.1002\/chem.201703602"},{"key":"e_1_2_7_17_1","unstructured":"\u00a0"},{"key":"e_1_2_7_18_2","volume-title":"The Alkaloids: Chemistry and Biology, Vol.\u200551","author":"Saxton J. E.","year":"1998"},{"key":"e_1_2_7_19_2","volume-title":"The Alkaloids: Chemistry and Biology, Vol.\u200566","author":"Kam T.-S.","year":"2008"},{"key":"e_1_2_7_20_2","volume-title":"Modern Alkaloids: Structure, Isolation, Synthesis and Biology","author":"Cuendet M.","year":"2008"},{"key":"e_1_2_7_21_2","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.1310459110"},{"key":"e_1_2_7_22_2","doi-asserted-by":"publisher","DOI":"10.1021\/acs.accounts.9b00246"},{"key":"e_1_2_7_23_1","unstructured":"For reviews on indole dearomatization and applications in synthesis see:"},{"key":"e_1_2_7_24_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.tet.2014.06.054"},{"key":"e_1_2_7_25_2","doi-asserted-by":"publisher","DOI":"10.1002\/adsc.201800789"},{"key":"e_1_2_7_26_2","doi-asserted-by":"publisher","DOI":"10.1039\/C8NP00098K"},{"key":"e_1_2_7_27_2","doi-asserted-by":"publisher","DOI":"10.1055\/s-0040-1707152"},{"key":"e_1_2_7_28_1","unstructured":"\u00a0"},{"key":"e_1_2_7_29_2","doi-asserted-by":"publisher","DOI":"10.1126\/science.aac9895"},{"key":"e_1_2_7_30_2","doi-asserted-by":"publisher","DOI":"10.1002\/anie.202000684"},{"key":"e_1_2_7_30_3","doi-asserted-by":"publisher","DOI":"10.1002\/ange.202000684"},{"key":"e_1_2_7_31_1","doi-asserted-by":"publisher","DOI":"10.1021\/acs.orglett.9b02612"},{"key":"e_1_2_7_32_1","doi-asserted-by":"publisher","DOI":"10.1039\/C8CS00790J"},{"key":"e_1_2_7_33_1","unstructured":"Select intramolecular examples:"},{"key":"e_1_2_7_34_2","doi-asserted-by":"publisher","DOI":"10.1021\/jacs.8b03302"},{"key":"e_1_2_7_35_2","doi-asserted-by":"publisher","DOI":"10.1021\/jacs.8b12965"},{"key":"e_1_2_7_36_2","doi-asserted-by":"publisher","DOI":"10.1021\/acscatal.0c03808"},{"key":"e_1_2_7_37_2","doi-asserted-by":"publisher","DOI":"10.1021\/acs.orglett.0c01622"},{"key":"e_1_2_7_38_2","doi-asserted-by":"publisher","DOI":"10.1021\/acscatal.0c01841"},{"key":"e_1_2_7_39_2","doi-asserted-by":"publisher","DOI":"10.1002\/anie.202016899"},{"key":"e_1_2_7_39_3","doi-asserted-by":"publisher","DOI":"10.1002\/ange.202016899"},{"key":"e_1_2_7_40_2","doi-asserted-by":"publisher","DOI":"10.1021\/jacs.1c07082"},{"key":"e_1_2_7_41_2","doi-asserted-by":"publisher","DOI":"10.1002\/anie.201802891"},{"key":"e_1_2_7_41_3","doi-asserted-by":"publisher","DOI":"10.1002\/ange.201802891"},{"key":"e_1_2_7_42_2","doi-asserted-by":"publisher","DOI":"10.1126\/science.abg0720"},{"key":"e_1_2_7_43_2","doi-asserted-by":"publisher","DOI":"10.1039\/D0QO01322F"},{"key":"e_1_2_7_44_1","unstructured":"\u00a0"},{"key":"e_1_2_7_45_2","doi-asserted-by":"publisher","DOI":"10.1021\/jacs.7b13616"},{"key":"e_1_2_7_46_2","doi-asserted-by":"publisher","DOI":"10.1002\/anie.201911144"},{"key":"e_1_2_7_46_3","doi-asserted-by":"publisher","DOI":"10.1002\/ange.201911144"},{"key":"e_1_2_7_47_1","unstructured":"For recent examples of electrochemcial dearomative indole annulations see:"},{"key":"e_1_2_7_48_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41467-019-13829-4"},{"key":"e_1_2_7_49_2","doi-asserted-by":"publisher","DOI":"10.1002\/anie.202000226"},{"key":"e_1_2_7_49_3","doi-asserted-by":"publisher","DOI":"10.1002\/ange.202000226"},{"key":"e_1_2_7_50_2","doi-asserted-by":"publisher","DOI":"10.1021\/jacs.8b13371"},{"key":"e_1_2_7_51_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41467-017-00873-1"},{"key":"e_1_2_7_52_1","unstructured":"\u00a0"},{"key":"e_1_2_7_53_2","doi-asserted-by":"publisher","DOI":"10.1055\/s-1990-21063"},{"key":"e_1_2_7_54_2","doi-asserted-by":"publisher","DOI":"10.1021\/jo00004a013"},{"key":"e_1_2_7_55_2","doi-asserted-by":"publisher","DOI":"10.1021\/jo00040a060"},{"key":"e_1_2_7_56_2","doi-asserted-by":"publisher","DOI":"10.1016\/0040-4039(93)85053-Y"},{"key":"e_1_2_7_57_2","doi-asserted-by":"publisher","DOI":"10.1039\/a900078j"},{"key":"e_1_2_7_58_2","doi-asserted-by":"publisher","DOI":"10.1002\/(SICI)1521-3765(19991001)5:10<2859::AID-CHEM2859>3.0.CO;2-R"},{"key":"e_1_2_7_59_1","doi-asserted-by":"publisher","DOI":"10.1021\/acscatal.7b02223"},{"key":"e_1_2_7_60_1","unstructured":"\u00a0"},{"key":"e_1_2_7_61_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja9078094"},{"key":"e_1_2_7_62_2","doi-asserted-by":"publisher","DOI":"10.1021\/acs.orglett.6b02192"},{"key":"e_1_2_7_63_1","unstructured":"Indole dearomatization via (3+2) cycloaddition can also be achieved through alternative methods including by opening strained rings or by conjugate addition into an electron deficient C2\u2212C3 \u03c0 bond. Select examples:"},{"key":"e_1_2_7_64_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja4042127"},{"key":"e_1_2_7_65_2","doi-asserted-by":"publisher","DOI":"10.1002\/anie.201405223"},{"key":"e_1_2_7_65_3","doi-asserted-by":"publisher","DOI":"10.1002\/ange.201405223"},{"key":"e_1_2_7_66_2","doi-asserted-by":"publisher","DOI":"10.1021\/jacs.5b05820"},{"key":"e_1_2_7_67_2","doi-asserted-by":"publisher","DOI":"10.1002\/anie.201900036"},{"key":"e_1_2_7_67_3","doi-asserted-by":"publisher","DOI":"10.1002\/ange.201900036"},{"key":"e_1_2_7_68_1","unstructured":"Reduction potentials are reported vs. the saturated calomel electrode (SCE). Ph2phen: 4 7-diphenyl-1 10-phenanthroline."},{"key":"e_1_2_7_69_1","doi-asserted-by":"publisher","DOI":"10.1055\/s-0035-1561297"},{"key":"e_1_2_7_70_1","unstructured":"Running experiments for longer did not increase the yield; vinyldiazo reagents will slowly convert to pyrazoles under the reaction conditions."},{"key":"e_1_2_7_71_1","doi-asserted-by":"publisher","DOI":"10.1021\/ja2093579"},{"key":"e_1_2_7_72_1","doi-asserted-by":"publisher","DOI":"10.1039\/C4SC03064H"},{"key":"e_1_2_7_73_1","unstructured":"Acylation of the bipyrazine ligand(s) is likely occurring leading to complex combinations of acylated species."},{"key":"e_1_2_7_74_1","doi-asserted-by":"publisher","DOI":"10.1039\/jr9460000948"},{"key":"e_1_2_7_75_1","unstructured":"A \u03b3-Ph vinyldiazo reagent was tested; see the Supporting Information for details. This reagent is prone to rapid pyrazole formation under irradiation."},{"key":"e_1_2_7_76_1","unstructured":"When enolizable acylating agents were used we observed fast decomposition of the vinyl diazo reagent."},{"key":"e_1_2_7_77_1","unstructured":"The indole functionalization with diazo reagents in ref.\u2005[7] was impacted by protic sources."},{"key":"e_1_2_7_78_1","doi-asserted-by":"publisher","DOI":"10.1002\/recl.19821011208"},{"key":"e_1_2_7_79_1","unstructured":"For recent examples of use see:"},{"key":"e_1_2_7_80_2","doi-asserted-by":"publisher","DOI":"10.1021\/jacs.0c10660"},{"key":"e_1_2_7_81_2","doi-asserted-by":"publisher","DOI":"10.1002\/anie.201202990"},{"key":"e_1_2_7_81_3","doi-asserted-by":"publisher","DOI":"10.1002\/ange.201202990"},{"key":"e_1_2_7_82_2","doi-asserted-by":"publisher","DOI":"10.3987\/COM-12-S(N)118"},{"key":"e_1_2_7_83_1","unstructured":"C2 C3-unsubstituted indoles were also competent under these conditions; the cycloaddition product from 5-bromoindole was obtained in 80\u2009% yield. See the Supporting Information."},{"key":"e_1_2_7_84_1","unstructured":"N-Substitution of indole with Troc-Cl is slow under the reaction conditions in the absence of vinyldiazo4\u2009a(\u224810\u2009% yield after 24\u2005h)."},{"key":"e_1_2_7_85_1","unstructured":"Relatedly it has been reported that \u03b1-carbonyl radicals\u2014derived photocatalytically from ethyl diazoacetate\u2014will add to N\u2212H indoles at C2. See Ref.\u2005[7]. When this reaction was tested as a competition experiment between 5-bromoindole and 5-methylindole both indoles reacted with similar rates. In a proposed (3+2) cycloaddition mechanism initiated by energy transfer with the vinyl diazoacetate (e.g. 4\u2009a\u21924\u2009a*) it is expected that4\u2009a*would have radical-type behavior. In the competition experiment herein the observed lack of indole selectivity and the C2-regioselective radical addition are both incongruous with this proposed mechanism."},{"key":"e_1_2_7_86_1","unstructured":"\u00a0"},{"key":"e_1_2_7_87_2","doi-asserted-by":"publisher","DOI":"10.1039\/p29960002663"},{"key":"e_1_2_7_88_2","doi-asserted-by":"publisher","DOI":"10.1039\/a908362f"},{"key":"e_1_2_7_89_1","unstructured":"One could envision the vinyldiazo acting as either a 1-electron nucleophile or a 2-electron nucleophile in attacking the radical cation intermediate. Single electron addition would be more consistent with the radical character at C3 of3+\u22c5."},{"key":"e_1_2_7_90_1","unstructured":"An intramolecular example was attempted where the indole and diazo were proximal and regioselective orientation would be favorable; however only small amounts of an intermolecular cycloaddition product were observed. The failed cycloaddition is consistent with the entropic difficulties of a 9-endoradical cyclization."},{"key":"e_1_2_7_91_1","unstructured":"The excitation of [Cr(PMP2Phen)3](BF4)3produces two main emission signals. The lower energy emission at 752\u2005nm represents the 2E state which is responsible for electron transfer. There is a higher energy emission in the 400\u2013500\u2005nm range. We observed less pronounced linear Stern\u2013Volmer quenching by both the indole and the vinyldiazoacetate. These CrIIIspecies are capable of energy transfer; we attribute this quenching to non-productive outcomes (e.g. pyrazole formation non-productive relaxation). See the Supporting Information."},{"key":"e_1_2_7_92_1","doi-asserted-by":"publisher","DOI":"10.1002\/1522-2675(200201)85:1<96::AID-HLCA96>3.0.CO;2-7"},{"key":"e_1_2_7_93_1","doi-asserted-by":"publisher","DOI":"10.1039\/b708910d"},{"key":"e_1_2_7_94_1","doi-asserted-by":"publisher","DOI":"10.1039\/dt9940000007"},{"key":"e_1_2_7_95_1","volume-title":"Synthetic Applications of 1,3-Dipolar Cycloaddition Chemistry Toward Heterocycles and Natural Products","author":"J\u00e4ger V.","year":"2002"},{"key":"e_1_2_7_96_1","unstructured":"\u00a0"},{"key":"e_1_2_7_97_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0040-4020(01)85844-0"},{"key":"e_1_2_7_98_2","doi-asserted-by":"publisher","DOI":"10.1002\/1099-0690(200105)2001:10<1971::AID-EJOC1971>3.0.CO;2-U"}],"container-title":["Angewandte Chemie International Edition"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/anie.202212187","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/full-xml\/10.1002\/anie.202212187","content-type":"application\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/anie.202212187","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/anie.202212187","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,8,22]],"date-time":"2023-08-22T05:31:10Z","timestamp":1692682270000},"score":1,"resource":{"primary":{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/10.1002\/anie.202212187"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,10,11]]},"references-count":108,"journal-issue":{"issue":"45","published-print":{"date-parts":[[2022,11,7]]}},"alternative-id":["10.1002\/anie.202212187"],"URL":"https:\/\/doi.org\/10.1002\/anie.202212187","archive":["Portico"],"relation":{},"ISSN":["1433-7851","1521-3773"],"issn-type":[{"value":"1433-7851","type":"print"},{"value":"1521-3773","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,10,11]]},"assertion":[{"value":"2022-08-17","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2022-10-11","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}],"article-number":"e202212187"}}