2C-B-FLY is 8-bromo-2,3,6,7-benzo-dihydro-difuran-ethylamine. The full name of the chemical is 2-(8-bromo-2,3,6,7-tetrahydrofuro[2,3-f] benzofuran-4-yl)ethanamine. It has been subject to little formal study, but its appearance as a designer drug has led the DEA to release analytical results for 2C-B-FLY and several related compounds.
In theory, dihydrodifuran analogues of any of the 2Cx / DOx family of drugs could be made, and would be expected to show similar activity to the parent compound. So in the same way that 2C-B-FLY is the dihydrodifuran analogue of 2C-B, the 8-iodo equivalent 2C-I-FLY would be the dihydrodifuran analogue of 2C-I, and the 8-methyl equivalent 2C-D-FLY would be the dihydrodifuran analogue of 2C-D.
Other related compounds can also be produced, where the alpha carbon of the ethylamine chain is methylated, the amphetamine derivative DOB-FLY can be made, this compound being the dihydrodifuran analogue of DOB, or conversely can be viewed as the saturated derivative of Bromo-DragonFLY.
Where only one methoxy group of a 2Cx drug is cyclised into a dihydrofuran ring, the resulting compound is known as a “hemifly”, and when an unsaturated furan ring is used, the compound is known as a “hemi-dragonfly”. The larger saturated hexahydrobenzodipyran ring derivatives have been referred to as “butterfly” compounds. The 8-bromo group can also be replaced by other groups to give compounds such as TFMFly.
A large number of symmetrical and unsymmetrical derivatives can be produced by using different combinations of ring systems. Because the 2- and 5- positions (using phenethylamine numbering scheme, 1,5-positions if numbered as benzodifuran) are not equivalent, all unsymmetrical combinations also have two possible positional isomers, with different potencies at the various 5-HT2 subtypes. Isomeric “Ψ“-derivatives with the oxygens positioned at the 2,6- positions, and mescaline analogues with the oxygens at 3,5- have also been made, but both are less potent than the corresponding 2,5- isomers. The symmetrical aromatic benzodifuran derivatives tend to have the highest binding affinity at 5-HT2A, but the saturated benzodifuran derivatives have higher efficacy, while the saturated benzodipyran derivatives are more selective for 5-HT2C. A large number of possible combinations have been synthesised and tested for activity, but these represent only a fraction of the many variations that could be produced.