Generally 3‐hetero‐substituted 2‐alken‐1‐ones were prepared from 1,3‐alkanediones, 3‐chloro‐2‐alken‐1‐ones, or conjugated ynones. The preparation of 3‐hetero‐substituted 2‐alken‐1‐ones was subjected to some limitations by these methods. By the reaction of 3‐(1‐imidazolyl)‐2‐alken‐1‐ones (I) and 3‐(3‐oxo‐1‐alkenyl)‐1‐methylimidazolium iodides (II) with nucleophiles, 3‐hetero‐substituted 2‐alken‐1‐ones could be obtained regioselectively in good yield under mild conditions. These results suggested that compounds I and II were concluded to be useful intermediates for the organic synthesis.