Benzocyclobutene
Benzocyclobutene is a benzene ring fused to a cyclobutane ring. It has chemical formula.
BCB is frequently used to create photosensitive polymers. BCB-based polymer dielectrics may be spun on or applied to various substrates for use in Micro Electro-Mechanical Systems and microelectronics processing. Applications include wafer bonding, optical interconnects, low-κ dielectrics, or even intracortical neural implants.
Reactions
Benzocyclobutene is a strained system which, upon heating to approximately 180 °C, causes the cyclobutene to undergo a conrotatory ring-opening reaction, forming o-xylylene. Since this process destroys the aromaticity of the benzene ring, the reverse reaction is highly favored.o-Xylylenes generated in this way have been used prolifically in cycloaddition reactions, which restore the aromaticity to the benzene ring, while forming a new annulated species.
Derivatives
The benzocyclobutene moiety has also appeared in a number of chemical compounds with pharmacological properties such as ivabradine and S33005.Additionally, cyclized phenethylamine psychedelic drugs containing the benzocyclobutene ring system, including TCB-2, tomscaline, bromotomscaline, and 2CBCB-NBOMe, have been described. A benzocyclobutene-derived amphetamine has been patented as well, and a benzocyclobutene containing designer drug, the substituted cathinone derivative 3,4-EtPV, has been sold in Europe. The benzocyclobutene derivative 2C-G-2 has also been claimed in a patent as an antiinflammatory, but no synthesis or activity data is provided so it is unclear if it has actually been made.