{"doi":"10.1002/hlca.201100150","title":"Introduction of Adjacent Oxygen‐Functionalities in Dimethyl Heptalenedicarboxylates","abstract":"<jats:title>Abstract</jats:title><jats:p>The bromination of dimethyl 8‐methoxy‐1,6,10‐trimethylheptalene‐4,5‐dicarboxylate (<jats:bold>6</jats:bold>; <jats:italic>Scheme 2</jats:italic>) with <jats:italic>N</jats:italic>‐bromosuccinimide (NBS) in <jats:italic>N</jats:italic>,<jats:italic>N</jats:italic>‐dimethylformamide (DMF) leads in acceptable yields to the corresponding 9‐bromoheptalenedicarboxylate <jats:bold>10</jats:bold> (<jats:italic>Table 1</jats:italic>). Ether cleavage of <jats:bold>6</jats:bold> with chlorotrimethylsilane (Me<jats:sub>3</jats:sub>SiCl)/NaI results in the formation of oxoheptalenedicarboxylate <jats:bold>13</jats:bold> in good yield (<jats:italic>Scheme 4</jats:italic>). The latter can be acetyloxylated to the (acetyloxy)oxoheptalenedicarboxylate <jats:bold>14</jats:bold> with Pb(OAc)<jats:sub>4</jats:sub> in benzene (<jats:italic>Scheme 5</jats:italic>). Oxo derivative <jats:bold>14</jats:bold>, in turn, can be selectively <jats:italic>O</jats:italic>‐methylated with dimethyl sulfate (DMS) in acetone to the (acetyloxy)methoxyheptalenedicarboxylates <jats:bold>15</jats:bold> and <jats:bold>15′</jats:bold> (<jats:italic>Scheme 6</jats:italic>). The AcO group of the latter can be transformed into a benzyl or methyl ether group by treatment with MeONa in DMF, followed by the addition of benzyl bromide or methyl iodide (<jats:italic>cf. Scheme 9</jats:italic>). Reduction of the ester groups of dimethyl 7,8‐dimethoxy‐5,6,10‐trimethylheptalene‐1,2‐dicarboxylate (<jats:bold>25′</jats:bold>) with diisobutylaluminium hydride (DIBAH) in tetrahydrofuran (THF) leads to the formation of the corresponding dimethanol <jats:bold>26′</jats:bold>, which can be cyclized oxidatively (IBX, dimethyl sulfoxide) to 8,9‐dimethoxy‐6,7,11‐trimethylheptaleno[1,2‐<jats:italic>c</jats:italic>]furan (<jats:bold>27</jats:bold>; <jats:italic>Scheme 11</jats:italic>).</jats:p>","journal":"Helvetica Chimica Acta","year":2011,"id":32686,"datarank":0.23228140637073158,"base_score":1.0986122886681096,"endowment":1.0986122886681096,"self_citation_contribution":0.16479184330021646,"citation_network_contribution":0.06748956307051514,"self_endowment_contribution":0.16479184330021646,"citer_contribution":0.06748956307051514,"corpus_percentile":null,"corpus_rank":null,"citation_count":2,"citer_count":1,"citers_with_citation_signal":1,"citers_with_endowment":1,"datacite_reuse_total":5,"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":172553,"name":"Danijela Stojnic","orcid":null,"position":1,"is_corresponding":false},{"id":172554,"name":"Anthony Linden","orcid":null,"position":2,"is_corresponding":false},{"id":172555,"name":"Khaled Abou‐Hadeed","orcid":null,"position":3,"is_corresponding":false},{"id":172556,"name":"Hans‐Jürgen Hansen","orcid":null,"position":4,"is_corresponding":false},{"id":172552,"name":"Frank Rogano","orcid":null,"position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"base_score":1.0986122886681096,"endowment":1.0986122886681096,"datacite_reuse_total":5,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"18998881","pmcid":null,"openalex_id":"https://openalex.org/W2017839069","authors":[],"funders":[],"total_grants":0,"fwci":0.1574,"citation_percentile":0.53820341,"influential_citations":0,"citation_trend":[{"year":2012,"count":1},{"year":2020,"count":1}],"oa_status":"bronze","license":null,"oa_locations":[{"url":"https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/hlca.201100150","host_type":"journal"},{"url":"https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/hlca.201100150","host_type":"BRONZE"},{"url":"https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/hlca.201100150","host_type":"publisher"},{"url":"https://doi.org/10.1002/hlca.201100150","host_type":"journal"},{"url":"https://www.zora.uzh.ch/51711","host_type":"repository"}],"fields_of_study":["Oxidative Organic Chemistry Reactions","Metal-Catalyzed Oxygenation Mechanisms","Vanadium and Halogenation Chemistry","Chemistry"],"mesh_terms":[],"keywords":["Chemistry","Dimethyl sulfate","Dimethyl ether","Dimethyl sulfoxide","Tetrahydrofuran","Medicinal chemistry","Bromide","Halogenation","Dimethylformamide","Benzyl bromide","Ether cleavage","Ether","Iodide","Methyl iodide","Dimethyl phthalate","Yield (engineering)","Magnesium bromide","Swern oxidation","Organic chemistry","Methanol","Catalysis","Solvent","Magnesium"],"sdg_mappings":[{"sdg_number":0,"sdg_label":"Clean water and sanitation"}],"linked_datasets":[{"doi":"10.5517/ccwk02h","title":"CCDC 820696: Experimental Crystal Structure Determination","publisher":"Cambridge Crystallographic Data Centre","resource_type":"Dataset"},{"doi":"10.5517/ccwk01g","title":"CCDC 820695: Experimental Crystal Structure Determination","publisher":"Cambridge Crystallographic Data Centre","resource_type":"Dataset"},{"doi":"10.5517/ccwjzzb","title":"CCDC 820693: Experimental Crystal Structure Determination","publisher":"Cambridge Crystallographic Data Centre","resource_type":"Dataset"},{"doi":"10.5517/ccwk00f","title":"CCDC 820694: Experimental Crystal Structure Determination","publisher":"Cambridge Crystallographic Data Centre","resource_type":"Dataset"},{"doi":"10.5517/ccwjzy9","title":"CCDC 820692: Experimental Crystal Structure Determination","publisher":"Cambridge Crystallographic Data Centre","resource_type":"Dataset"}],"clinical_trials":[],"software_tools":[],"database_accessions":[],"source":"live","citation_network_status":"fetched"},"created_at":"2026-06-09T14:06:10.195083Z","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":[]}