New homologation of 2-hydroxy and 2-mercapto benzylic alcohols

✍ Scribed by Prabir K. Choudhury; Juan Almena; Francisco Foubelo; Miguel Yus

• Publisher: Elsevier Science
• Year: 1997
• Tongue: French
• Weight: 647 KB
• Volume: 53
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(97)10161-2

✦ Synopsis

The reaction of benzo-l,3-dioxanes or benzo-l,3-oxathianes 1 [easily prepared from 2hydtoxy or 2-mercapto bonzylic alcohols (3 or 4, respectively) and carbonyl compounds] with an excess of lithium and a catalytic amount of DTBB (4.5 tool %) in THF at room temperature or -78*(2 leads, after hydrolysis with water, to the corresponding homobeazylic alcohols 2. Cyclisation of compounds 2 under acidic (85% H3PO4) or neutral (Ph3P/DIAD) conditions affords the expected heterocycles 5.