Metal-free and efficient approach to 4-thiocyanated 2H-chromenes via TFA-mediated cascade cyclization of 2-propynolphenols. Issue 18 (2nd May 2019) - Yang, Tao
Graphical abstract: Highlights: TFA mediated synthesis of 4-thiocyanated 2 H -chromenes in good to excellent yields. The 4-thiocyanated 2 H -chromenes are versatile intermediates in organic synthesis. This approach can be enlarged to gram scale. This process involves a SCN-containing alleneyl intermediate through SN 1 way. Abstract: A metal-free, Brønsted acid-mediated cascade cyclization of 2-propynolphenols for efficient synthesis of various 4-thiocyanated 2 H -chromenes is developed by using KSCN as the thiocyanated source. This reaction was characterized by readily prepared starting materials, bearing good functional group tolerance and excellent yields. Moreover, the obtained 4-thiocyanated 2 H -chromenes could be further derivated to potential bioactive and pharmaceutical molecules.