A simple Lewis acid induced reaction of phenols with electrophiles: Synthesis of functionalized 4H-chromenes and ortho-benzylphenols

Abstract

Lewis acid ZnCl₂ promoted cyclization protocol to 4H-chromenes is accomplished, using readily available phenols and acetophenones as starting materials. Interestingly, the process is feasible under the solvent free environment. Synthesis of a variety of 4H-chromenes have been accomplished using this strategy. In addition, this concept is extended to the synthesis of ortho-benzylphenols by treating phenols either with styrenes or secondary benzylic alcohols.

Graphical Abstract

Keywords:

• 4H-chromenes
• phenol
• ketones
• chalcones
• Lewis acid

Acknowledgment

We are very much thankful to the Council of Scientific and Industrial Research [(CSIR), No. 02(0262)/16/EMR-II], New Delhi, for financial support and C.B.S. thank UGC for the award of a research fellowship.