β-Carboline, which had an acyl group derived from l-proline at the 9-position, reacted with allyltributyltin and 2, 2, 2-trichloroethyl chloroformate to afford an 1-allyl-1, 2-dihydro-β- carboline derivative in a diastereoselective manner. The chiral acyl group at N-9 was readily eliminated by aqueous alkali to give a corresponding carboxylic acid. The formed 1-allyl-1, 2- dihydro-β-carboline was transformed via two reduction steps to 1-allyl-1, 2, 3, 4-tetrahydro ...