Intramolecular Heck Reaction for the Synthesis of Isochromanes under Ambient and High pressure

✍ Scribed by Tietze, Lutz F. ;Burkhardt, Olaf ;Henrich, Marielouise

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 535 KB
• Volume: 1997
• Category: Article
• ISSN: 0947-3440
• DOI: 10.1002/jlac.199719970516

✦ Synopsis

Abstract

The iodoarenes 9 and 10, bearing (E)‐ and (Z)‐alkene moieties, respectively, easily prepared by alkylation of the corresponding alcohols 7a–c and 8a–c with 2 iodobenzyl iodide, undergo intramolecular Heck reactions to give the isochromanes 12–15a–c in good yields. The selectivity of the reaction depends on the size of the substituent R in 9 and 10; increasing bulkiness of R leads to a decrease in diastereoselectivity and an increase in regioselectivity. High‐pressure experiments confirm the proposed mechanism and show that bromoarenes such as 11, which tend to be unreactive at ambient pressure, give good results when the cyclisation is performed under high pressure.