The whole point of the 2012 legislation was to stop playing that kind of legislative whack-a-mole. It doesn't attempt to exhaustively enumerate specific compounds, rather it bans broadly any cannabinoid receptor agonist in a broad umbrella of structural classes, including "any material, compound, mixture, or preparation which contains any quantity of cannabimimetic agents, or which contains their salts, isomers, and salts of isomers".
As a side note, even outside of this particular legislation there are two ways the government reacts more quickly than legislation to new designer drugs: the DEA can administratively do an emergency schedule of them (as was done for many of the cannabanoids in Spice/K2/etc in 2010--the 2012 act extends the allowed duration of emergency scheduling to 2 years), and the Drug Analogs Act automatically makes any "substantially similar" chemicals scheduled on the same footing as their analogs.