Enynones in organic synthesis. III. A novel synthesis of phenols

✍ Scribed by Peter A. Jacobi; Joseph I. Kravitz

• Publisher: Elsevier Science
• Year: 1988
• Tongue: French
• Weight: 241 KB
• Volume: 29
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)88463-4

✦ Synopsis

Enynones are converted to phenols by an acid catalyzed process which can be controlled to give either of two regioisomeric series of products.

During the course of efforts aimed at converting the acetylenic enone 1 to the acorone precursor 2,l.z we were surprised to find that collidine p-toluenesulfonate (CPTS) catalyzed a very efficient transformation of 1 to the dihydronaphthol derivative 3a at 250° C in mesitylene. None of the desired spirocycle 2 could be detected, and the 2 1 30

only other material isolated was a trace amount of the corresponding naphthol derivative formed by air oxidation of 3a.

This transformation works equally well with either the E-or Z-isomer of 1, and mechanistic studies indicate that the initial step is an acid catalyzed enolization of 1 to give the dienyne derivative 4a (Scheme 1). At this stage, we believe,