Ketene. Part 26. The reactions of 3,4-dihydroisoquinoline N-oxide with ketenes, and an attempted synthesis of 3,4-dihydro-3,3-dimethylquinoline N-oxide

3,4-Dihydroisoquinoline N-oxide reacts with dimethylketene to form a 1 : 2 adduct (8) in addition to compounds (6) and (7). With cyano-t-butylketene and ethoxycarbonyl-t-butylketene the adducts (9a) and (9b) are formed. 3,3-Dimethyl-1,2,3,4-tetrahydroquinoline (21a) has been synthesized, but attempts to convert this into the nitrone (20b) were unsuccessful.