Reaction of 3,4-dihydroisoquinoline (I) with benzyl chloroformate in acetonitrile afforded the isoquinolinium salt (II), which was coupled in situ with 2-(tert-butyldimethylsilyloxy)furan (III) to produce a diastereomeric mixture of threo (IV) and erythro (V) adducts. After chromatographic isolation of the desired threo-isomer (IV), catalytic hydrogenation of the furanone double bond and simultaneous removal of the carbobenzoxy group furnished the tetrahydroisoquinoline (VI). This was converted to the target sulfonamide using p-toluenesulfonyl chloride (VII) and triethylamine. The enantiomers were then separated by means of chiral HPLC.