Palladium-Catalyzed Cyclization of Silyl-Substituted Bis(homo)propargylic Alcohols to 2,3-Dihydrofurans

✍ Scribed by Silke Schabbert; Ernst Schaumann

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 321 KB
• Volume: 1998
• Category: Article
• ISSN: 1434-193X
• DOI: 10.1002/(sici)1099-0690(199809)1998:9<1873::aid-ejoc1873>3.0.co;2-7

✦ Synopsis

Ring-opening of oxiranes 1 by the silicon-and sulfur-phenylthiofurans 5 is achieved by reaction with palladium(II) acetate. The corresponding furans 7 are obtained when functionalized propargyl anions 2 yields the corresponding alk-4-yn-1-ols 3. Cyclization of 3 to 2,3-dihydro-4-copper(II) chloride is added to the reaction mixtures. Ϫ[CH 2 ] 4 Ϫ 60 70 at Ϫ78°C; for the complete conversion of disubstituted oxi-3i, 3j Me SiMe 2 Ph 41 64

ranes the temperature is allowed to rise to Ϫ10°C. An exception is the ring-opening of the disubstituted epoxide 1e [a] Isolated yields of pure products.