1H,5H,11H-(1)Benzopyrano(6,7,8-ij)quinolizine-10-carboxylic acid, 2,3,6,7-tetrahydro-11-oxo-, 1,1-dimethylethyl ester 62669-75-4 EINECS 263-688-3 tert-Butyl 2,3,6,7-tetrahydro-11-oxo-7H,5H,11H-(1)benzopyrano(6,7,8-ij)quinolizine-10-carboxylate