| Autor: |
Hinkle RJ; Department of Chemistry , William & Mary , P.O. Box 8795, Williamsburg , Virginia 23187-8795 , United States., Speer DJ; Department of Chemistry , William & Mary , P.O. Box 8795, Williamsburg , Virginia 23187-8795 , United States., Carnell BB; Department of Chemistry , William & Mary , P.O. Box 8795, Williamsburg , Virginia 23187-8795 , United States., Kanter BL; Department of Chemistry , William & Mary , P.O. Box 8795, Williamsburg , Virginia 23187-8795 , United States., Pike RD; Department of Chemistry , William & Mary , P.O. Box 8795, Williamsburg , Virginia 23187-8795 , United States. |
| Abstrakt: |
Tetracyclic 6 H -naphtho[2,1- c ]chromenes are expeditiously synthesized through a BF 3 ·OEt 2 -mediated, three-step cascade reaction, creating new central pyran and aromatic rings. The cascade involves the addition of phenol-derived alkynyl substrates to BF 3 -activated aldehydes followed by alkyne-Prins cyclization, Friedel-Crafts reaction, and final elimination. Aliphatic and electron-deficient aromatic aldehydes afford the products in 50-74% isolated yields, but benzaldehyde and tolualdehyde resulted in lower yields. X-ray analysis of a p -bromophenyl derivative ( 5aA ) shows the two aromatic moieties are twisted by 28° to create a helical backbone. |
