Pictet-Spengler condensation of phenylalanine (I) with formaldehyde and HCl provided tetrahydroisoquinoline (II). Reduction of the carboxylic acid (II) to alcohol (III) was then performed in the presence of borane and BF3-Et2O. Subsequent protection of amino and hydroxyl groups of (III) with carbonyl diimidazole in boiling THF produced the cyclic carbamate (IV). After chlorosulfonation of (IV), the resulting sulfonyl chloride (V) was treated with ammonia in acetonitrile to furnish sulfonamide (VI). Finally, basic hydrolysis of the oxazolidinone (VI), followed by acid decarboxylation yielded the title compound.