FOERFARANDE FOER FRAMSTAELLNING AV HETEROCYKLISKA FOERENINGAR

The invention relates to a process for the preparation of compounds of general formula (I)whereinR' represents a hydrogen atom or a C1-10 alkyl, C3-7 cycloalkyl, C3-7 cycloalkyl-(C1-4)alkyl, C3-6 alkenyl, C3-10 alkynyl, phenyl or phenyl-(C1-3)alkyl group, and one of the groups represented by R2, R3 and R4 is a hydrogen atom or a C,.6 alkyl, C3-7 cycloalkyl, C2-6 alkenyl or phenyl-IC1-3)alkyl group and each of the other two groups, which may be the same or different, represents a hydrogen atom or a C1-6 alkyl group; or a salt or protected derivative thereof by cyclisation of a compound of general formula (ll)wherein X represents a hydrogen atom or a halogen atom and R', R2, R3, and R4 are as defined above, or a salt or a protected derivative thereof.The compounds of formula (I) are potent and selective antagonists at "neuronal" 5-hydroxytryptamine receptors.