275-51-4 AZULENE Azunamic Bicyclo(5.3.0)-1,3,5,7,9-decapentaene Bicyclo(5.3.0)-deca-2,4,6,8,10-pentaene Bicyclo(5.3.0)decapentaene Cyclopentacycloheptene EINECS 205-993-6 NSC 89248