A novel process for preparing 7,8-dichloro-1,2,3,4-tetrahydroisoquinoline by cyclizing N-acetyl-2,3-dichlorobenzylaminoacetaldehyde dimethyl acetal with a Lewis acid, reducing, and hydrolyzing the resulting acylated isoquinoline is disclosed.

Thiadiazolo- and oxadiazolotetrahydroisoquinoline compounds are inhibitors of phenylethanolamine N-methyltransferase.

A method of synthesizing nitrogen heterocycles such as indoles, indolines, oxindoles, quinolines, isoquinolines, and isoquinolones, all of which are pharmacologically active. The method involves cyclizing a haloaryl alkene in the presence of a catalytically effective amount of a palladium(II) ion source and in the presence of a cyclizing promoting base such as an alkali metal salt.

1,2,3,4-Tetrahydroisoquinoline compounds having 7- and/or 8-sulfur substituents are inhibitors of phenylethanolamine N-methyltransferase.