{"doi":"10.1002/chem.201304160","title":"Carbocations as Lewis Acid Catalysts in Diels–Alder and Michael Addition Reactions","abstract":"<jats:title>Abstract</jats:title><jats:p>In general, Lewis acid catalysts are metal‐based compounds that owe their reactivity to a low‐lying empty orbital. However, one potential Lewis acid that has received negligible attention as a catalyst is the carbocation. We have demonstrated the potential of the carbocation as a highly powerful Lewis acid catalyst for organic reactions. The stable and easily available triphenylmethyl (trityl) cation was found to be a highly efficient catalyst for the Diels–Alder reaction for a range of substrates. Catalyst loadings as low as 500 ppm, excellent yields, and good <jats:italic>endo</jats:italic>/<jats:italic>exo</jats:italic> selectivities were achieved. Furthermore, by changing the electronic properties of the substituents on the tritylium ion, the Lewis acidity of the catalyst could be tuned to control the outcome of the reaction. The ability of this carbocation as a Lewis acid catalyst was also further extended to the Michael reaction.</jats:p>","journal":"Chemistry – A European Journal","year":2014,"id":678232,"datarank":0.6628260911694899,"base_score":4.418840607796598,"endowment":4.418840607796598,"self_citation_contribution":0.6628260911694899,"citation_network_contribution":0.0,"self_endowment_contribution":0.6628260911694899,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":82,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":null,"is_data_producer":false,"deposit_databanks":null,"is_oa":false,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":null,"fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1772075,"name":"Johan Franzén","orcid":null,"position":1,"is_corresponding":false},{"id":1772071,"name":"Juho Bah","orcid":null,"position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"resolved":true,"title":"Carbocations as Lewis Acid Catalysts in Diels–Alder and Michael Addition Reactions","abstract":"<jats:title>Abstract</jats:title><jats:p>In general, Lewis acid catalysts are metal‐based compounds that owe their reactivity to a low‐lying empty orbital. However, one potential Lewis acid that has received negligible attention as a catalyst is the carbocation. We have demonstrated the potential of the carbocation as a highly powerful Lewis acid catalyst for organic reactions. The stable and easily available triphenylmethyl (trityl) cation was found to be a highly efficient catalyst for the Diels–Alder reaction for a range of substrates. Catalyst loadings as low as 500 ppm, excellent yields, and good <jats:italic>endo</jats:italic>/<jats:italic>exo</jats:italic> selectivities were achieved. Furthermore, by changing the electronic properties of the substituents on the tritylium ion, the Lewis acidity of the catalyst could be tuned to control the outcome of the reaction. The ability of this carbocation as a Lewis acid catalyst was also further extended to the Michael reaction.</jats:p>","is_dataset_classified":null,"base_score":4.418840607796598,"endowment":4.418840607796598,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"24375806","pmcid":null,"openalex_id":"https://openalex.org/W1985652286","authors":[],"funders":[],"total_grants":0,"fwci":3.7055,"citation_percentile":0.92905496,"influential_citations":0,"citation_trend":[{"year":2014,"count":6},{"year":2015,"count":10},{"year":2016,"count":6},{"year":2017,"count":11},{"year":2018,"count":8},{"year":2019,"count":11},{"year":2020,"count":5},{"year":2021,"count":7},{"year":2022,"count":7},{"year":2023,"count":3},{"year":2024,"count":3},{"year":2025,"count":4},{"year":2026,"count":1}],"oa_status":"closed","license":"http://onlinelibrary.wiley.com/termsAndConditions#vor","oa_locations":[{"url":"https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fchem.201304160","host_type":"publisher"},{"url":"https://chemistry-europe.onlinelibrary.wiley.com/doi/pdf/10.1002/chem.201304160","host_type":"publisher"},{"url":"https://doi.org/10.1002/chem.201304160","host_type":"journal"},{"url":"https://pubmed.ncbi.nlm.nih.gov/24375806","host_type":"repository"}],"fields_of_study":["Chemical Synthesis and Reactions","Asymmetric Synthesis and Catalysis","Synthetic Organic Chemistry Methods"],"mesh_terms":[],"keywords":["Carbocation","Lewis acids and bases","Catalysis","Chemistry","Lewis acid catalysis","Reactivity (psychology)","Acid catalysis","Organic chemistry","Diels–Alder reaction","Medicinal chemistry","Photochemistry","Organocatalysis","Carbocations","Michael Addition","Diels-alder Reactions","Tritylium Ions"],"sdg_mappings":[{"sdg_number":0,"sdg_label":"Clean water and sanitation"}],"linked_datasets":[],"clinical_trials":[],"software_tools":[],"database_accessions":[],"source":"live","citation_network_status":"fetched"},"created_at":"2026-08-17T05:06:57.635510Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}