a domino reaction as involving two or more bond-forming transformations which take place under the same reaction conditions, without adding additional reagents and catalysts, and in which the subsequent reactions result as a consequence of the functionality formed by bond formation or fragmentation in the previous step.That is to say, a domino reaction is strictly defined as a process in which two or more bond-forming transformations occur based on functionalities formed in the previous step. Furthermore, no additional reagents, catalysts, or additives can be added to the reaction vessel, nor can reaction conditions be changed.