| abstract |
The novel title cpds. are of formula (where R1, R3, R4, R5 and R8 are H or lower alkyl, R2 is H, lower alkyl or phenyl, an R6 and R7 are lower alkyl) including their acceptable salts. are prepd. by cyclisation of tetrahydropyridine derivs. of formula: with a Lewis acid, e.g. HBr, phosphoric acid, AlCl3 or AlBr3 at 10-200 degrees C. |