BF3 ⋅ Et2O‐Mediated Annulation of 2‐Alkynyl Biaryls with N‐(Arylthio) Succinimides: An Efficient Approach to Access 9‐Sulfenylphenanthrenes

A simple and effective method for the synthesis of 9sulfenylphenanthrenes was developed via BF3 center dot OEt2-mediated annulation of 2-alkynyl biaryls with N-arylthio succinimides at room temperature. Through this methodology, a series of 9- sulfenylphenanthrenes could be efficiently and conveniently obtained in good to excellent yields under mild and metal-free conditions.