Synthesis of Polysubstituted 2H‐Pyran‐2‐ones or Phenols via One‐Pot Reaction of (E)‐β‐Chlorovinyl Ketones and Electron‐Withdrawing Group Substituted Acetates or β‐Diketones

This paper describes a facile one‐pot synthesis of highly functionalized 2H‐pyran‐2‐ones and phenols through a base‐promoted annulation of readily available β‐chlorovinyl ketones with various active methylene compounds. Conjugate addition of electron‐withdrawing group substituted acetates to allenone intermediates and direct conjugate addition of β‐diketones to β‐chlorovinyl ketones reveal versatile electrophilic pathways of β‐chlorovinyl ketones under different reaction conditions. In particular, cyclocondensation is regiospecific for 3,5‐disubstituted phenols. Moreover, the utility of [3+3] cyclocondensation is further illustrated by the concise synthesis of benzofuran derivative and penta‐ or hexa‐substituted phenol construction. This paper describes a facile one‐pot synthesis of highly functionalized 2H‐pyran‐2‐ones and a regiospecific construction of 3,5‐disubstituted phenols via base‐promoted annulation of readily available β‐chlorovinyl ketones with various active methylene compounds. The detailed experimental studies demonstrated that versatile electrophilic pathways of β‐chlorovinyl ketones could be observed by using different nucelophilic species.