Non Classic cannabinoids as CP-55, 940 are similar to THC but without the pyran ring. In general these compounds show poor selectivity. Aminoalkylindoles as WIN 55212-2, potent CB1 and CB2 agonist, AM-630, the first CB2 selective antagonist of this class and AM-1241, potent selective CB2 agonist. Besides these groups there are other structures such as benzofurans (LY320135), diarilpirazoles (rimonabant, SR141716), sulfonamide derivatives, quinolinones derivatives (GW-842166X), etc. There are also some structures inspired in endogenous cannabinoids, such as the CB1 selective agonist O-1812.