Condensation of glyoxal, formaldehyde and anilines lead to the formation of 2,4,6,8- tetraphenyl and substituted phenyl 2,4,6,8-tetraazabicyclo [3.3.0] octanes. The reactions are sensitive to pH and temperature. Ortho derivatives of anilines do not participate in this condensation. X-ray structural determination reveals a cis-dienvelope geometery about the two fused rings.