BTW note that the p-(pseudo)halogen PEAs increase in potency down the period i.e. -Br > -Cl > -F i.e. the opposite of the aminorex class. That suggests that the (M)AR scaffold only just fits into the receptor. The above paper included analogues with o-F substitution. A reference states that the 3,4-dimethyl derivative isn't very active. The m-TFM analogue is slightly more potent than AR,
www.ncbi.nlm.nih.gov
If I were looking into multiple ring substitutions, I would imagine that the 2,5-dimethoxy (if a TFM fits, an -OCH3 will likely do so) 4-F. This MAY lend 5HT2a affinity.
If you are looking for something like MDMA (but better), you are going to have to find a substitution that increases serotonin activity, a second one that acts like plain AR but has a duration similar to the p-Me. I'm sure those of you who have studied things like fenfluramine will realise that it's the bulk rather than the electronic character that matters.
Of course, their are some entirely new scaffolds that are currently being considered as drugs of abuse i.e. become schedule 1 in the USA.
Aminorex analogs - PMC
Aminorex (5-phenyl-4,5-dihydro-1,3-oxazol-2-amine) and 4-methylaminorex (4-methyl-5-phenyl-4,5-dihydro-1,3-oxazol-2-amine) are psychostimulants that have long been listed in Schedules IV and I of the UN Convention on Psychotropic Substances of 1971. ...

If I were looking into multiple ring substitutions, I would imagine that the 2,5-dimethoxy (if a TFM fits, an -OCH3 will likely do so) 4-F. This MAY lend 5HT2a affinity.
If you are looking for something like MDMA (but better), you are going to have to find a substitution that increases serotonin activity, a second one that acts like plain AR but has a duration similar to the p-Me. I'm sure those of you who have studied things like fenfluramine will realise that it's the bulk rather than the electronic character that matters.
Of course, their are some entirely new scaffolds that are currently being considered as drugs of abuse i.e. become schedule 1 in the USA.