title: C-H insertion approach to the synthesis of endo,exo-furofuranones: synthesis of (+/-)-asarinin, (+/-)-epimagnolin A, and (+/-)-fargesin.
abstract: A series of novel 5-aryl-4-aryloxymethyl-3-diazotetrahydrofuran-2-ones (12, 24, and 35a/b) have been prepared and found to undergo regio- and stereoselective C-H insertion reactions to afford 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane-8-ones (18, 26, and 36a/b) with endo,exo stereochemistry. Subsequent reduction of the lactone ring and cyclization of the resulting diols 27 and 37a/b permitted the synthesis of three endo,exo-furofuran lignans: asarinin (2), fargesin (3), and epimagnolin A (4). En route to the key diazo compounds 24 and 35a/b, a modified procedure for the Ghosez keteniminium-olefin cyclization was developed, which was required to minimize the decomposition of acid-sensitive functional groups such as electron-rich benzylic ethers that were present in the target compounds 2-4.
authors.affiliation: Department of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UK. rcb1@soton.ac.uk
authors.forename: R C
authors.initials: RC
authors.lastname: Brown
authors.forename: C J
authors.initials: CJ
authors.lastname: Bataille
authors.forename: G
authors.initials: G
authors.lastname: Bruton
authors.forename: J D
authors.initials: JD
authors.lastname: Hinks
authors.forename: N A
authors.initials: NA
authors.lastname: Swain
mesh_terms: D018926:Anti-Allergic Agents / Q000138:chemical synthesis; D000924:Anticholesteremic Agents / Q000138:chemical synthesis; D000959:Antihypertensive Agents / Q000138:chemical synthesis; D000970:Antineoplastic Agents / Q000138:chemical synthesis; D000975:Antioxidants / Q000138:chemical synthesis; D004149:Dioxoles / Q000138:chemical synthesis*; D004365:Drugs, Chinese Herbal / Q000138:chemical synthesis; D005663:Furans / Q000138:chemical synthesis; D017705:Lignans / Q000138:chemical synthesis*; D008031:Lignin / Q000031:analogs & derivatives* / Q000138:chemical synthesis*; D010975:Platelet Aggregation Inhibitors / Q000138:chemical synthesis
chemical_list: D018926:Anti-Allergic Agents; D000924:Anticholesteremic Agents; D000959:Antihypertensive Agents; D000970:Antineoplastic Agents; D000975:Antioxidants; D004149:Dioxoles; D004365:Drugs, Chinese Herbal; D005663:Furans; D017705:Lignans; D010975:Platelet Aggregation Inhibitors; C094148:magnolin; D008031:Lignin; C054125:sesamin