MDMAI can be thought of as a cyclised analogue of MDMA where the alpha-methyl carbon of the alkylamino side chain has been joined back round to the 6-position of the aromatic ring to form an indane ring system. This changes the core structure of the molecule from phenethylamine to aminoindane, and causes the pharmacological properties of the two compounds to be substantially different.[1]
References
^ abOberlender R, Nichols DE (1990). "(+)-N-methyl-1-(1,3-benzodioxol-5-yl)-2-butanamine as a discriminative stimulus in studies of 3,4-methylenedioxy-methamphetamine-like behavioral activity". J Pharmacol Exp Ther. 255 (3): 1098–1106. PMID1979813.