was cooled to room temperature rt crushed ice was added and the mixture was slowly basified with naoh solid and 2 m naoh to ph u02dc 7 the aqueous layer was extracted with hexane ethyl acetate 1 1 solution 3 times the pooled organic layers were dried over magnesium sulfate the mixture was filtered and the solvents were removed under vacuum to give 8 benzylidene 5 6 7 8 tetrahydro quinoline 2 as a brown solid 6 7 dihydro 5h quinolin 8 one 3 a solution of 2 in dichloromethane 100 ml and methanol 500 ml was cooled to u2212 78 u00b0 c and charged with ozone oxygen 3 psi 1 5 ampere the dark brown solution turned yellow after several hours when 2 was consumed tlc ozone oxygen flow was stopped the reaction mixture was purged with nitrogen for 10 m methyl sulfide 6 ml was added and the mixture was stirred for 30 m at 0 u00b0 c the solvents were removed under vacuum and the residue was dissolved in 1 n hcl 500 ml and washed with diethyl ether 4 u00d7 150 ml the aqueous layer was basified to ph u02dc 7 with naoh s and extracted with ethyl acetate 2 u00d7 200 ml the pooled ethyl acetate layers were dried over.