title: Total synthesis of atropurpuran.
abstract: Due to their architectural intricacy and biological significance, the synthesis of polycyclic diterpenes and their biogenetically related alkaloids have been the subject of considerable interest over the last few decades, with progress including the impressive synthesis of several elusive targets. Despite tremendous efforts, conquering the unique structural types of this large natural product family remains a long-term challenge. The arcutane diterpenes and related alkaloids, bearing a congested tetracyclo[5.3.3.0(4,9).0(4,12)]tridecane unit, are included in these unsolved enigmas. Here we report a concise approach to the construction of the core structure of these molecules and the first total synthesis of (±)-atropurpuran. Pivotal features of the synthesis include an oxidative dearomatization/intramolecular Diels-Alder cycloaddition cascade, sequential aldol and ketyl-olefin cyclizations to assemble the highly caged framework, and a chemoselective and stereoselective reduction to install the requisite allylic hydroxyl group in the target molecule.
authors.affiliation: Key Laboratory of Drug Targeting and Drug Delivery Systems of the Ministry of Education, Department of Chemistry of Medicinal Natural Products, West China School of Pharmacy, and State Key Laboratory of Biotherapy, Sichuan University, No. 17, Section 3, Renmin Nan Road, Chengdu 610041, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Gong
authors.affiliation: Key Laboratory of Drug Targeting and Drug Delivery Systems of the Ministry of Education, Department of Chemistry of Medicinal Natural Products, West China School of Pharmacy, and State Key Laboratory of Biotherapy, Sichuan University, No. 17, Section 3, Renmin Nan Road, Chengdu 610041, China.
authors.forename: Huan
authors.initials: H
authors.lastname: Chen
authors.affiliation: Key Laboratory of Drug Targeting and Drug Delivery Systems of the Ministry of Education, Department of Chemistry of Medicinal Natural Products, West China School of Pharmacy, and State Key Laboratory of Biotherapy, Sichuan University, No. 17, Section 3, Renmin Nan Road, Chengdu 610041, China.
authors.forename: Xiao-Yu
authors.initials: XY
authors.lastname: Liu
authors.affiliation: Key Laboratory of Drug Targeting and Drug Delivery Systems of the Ministry of Education, Department of Chemistry of Medicinal Natural Products, West China School of Pharmacy, and State Key Laboratory of Biotherapy, Sichuan University, No. 17, Section 3, Renmin Nan Road, Chengdu 610041, China.
authors.forename: Zhi-Xiu
authors.initials: ZX
authors.lastname: Wang
authors.affiliation: Key Laboratory of Drug Targeting and Drug Delivery Systems of the Ministry of Education, Department of Chemistry of Medicinal Natural Products, West China School of Pharmacy, and State Key Laboratory of Biotherapy, Sichuan University, No. 17, Section 3, Renmin Nan Road, Chengdu 610041, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Nie
authors.affiliation: Key Laboratory of Drug Targeting and Drug Delivery Systems of the Ministry of Education, Department of Chemistry of Medicinal Natural Products, West China School of Pharmacy, and State Key Laboratory of Biotherapy, Sichuan University, No. 17, Section 3, Renmin Nan Road, Chengdu 610041, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Qin
mesh_terms: D000447:Aldehydes / Q000737:chemistry; D000475:Alkenes / Q000737:chemistry; D001688:Biological Products / Q000138:chemical synthesis*; D003500:Cyclization; D061565:Cycloaddition Reaction / Q000379:methods*; D004224:Diterpenes / Q000138:chemical synthesis*; D015394:Molecular Structure; D010084:Oxidation-Reduction; D013237:Stereoisomerism
chemical_list: D000447:Aldehydes; D000475:Alkenes; D001688:Biological Products; D004224:Diterpenes; C569135:atropurpuran; C116609:3-hydroxybutanal