When in a cycloaddition charged or radical intermediates are involved or when the cycloaddition result is obtained in a series of reaction steps they are sometimes called formal cycloadditions to make the distinction with true pericyclic cycloadditions .
When charged or radical intermediates are involved in a cycloaddition , or when the cycloaddition result is found in a series of reaction steps , they are sometimes called formal cycloadditions to make a difference from true pericyclic cycloadditions .