Stereoselective Intramolecular Dearomatizative [4+2] Cycloaddition of Linked Ethynylnaphthol–Benzofuran Systems. Issue 46 (8th December 2017)

• Record Type: Journal Article
• Authors: Beppu, Shota; Arae, Sachie; Furusawa, Masaki; Arita, Kosuke; Fujimoto, Hitoshi; Sumimoto, Michinori; Imahori, Tatsushi; Igawa, Kazunobu; Tomooka, Katsuhiko; Irie, Ryo
• Is Part Of: European journal of organic chemistry. Issue 46(2017)
• Page Start: 6914
• Page End: 6918
• Publication Date: 2017-12-08
• Subjects: Cycloaddition -- Brønsted base catalysis -- Organocatalysis -- Quinone methides -- Asymmetric catalysis; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.201701481
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract : A base‐catalyzed stereoselective intramolecular dearomatizative [4+2] cycloaddition of o ‐phenylene‐linked ethynylnaphthol–benzofuran systems was explored. In this reaction, we presume the involvement of electrophilic vinylidene o ‐quinone methides (4π), which add across the electron‐rich furan double bonds (2π) to produce elaborate, fused oxa‐polyheterocyclic frameworks with consecutive quaternary and tertiary asymmetric carbon atoms as single diastereomers. The catalytic and enantioselective synthesis of these chiral fused polyheterocyclic structures is also feasible with the use of a prevalent cinchonidine or cinchonine chiral base. Abstract : Vinylidene o ‐quinone methide (VQM) intermediates generated by base‐catalyzed 1, 5‐H shift of ethynylnaphthol–benzofuran systems undergo stereoselective intramolecular dearomatizative [4+2] cycloaddition to give oxa‐polyheterocyclic compounds with consecutive quaternary and tertiary asymmetric carbon atoms as single diastereomers. An enantioselective version of this reaction is also achieved.