A regioselective alkylation of naphthyridines 4a-d, through the action of ethylchloroformate and benzylstannane 5, afforded the benzyl substituted dihydronaphthyridines 3a-d. These key intermediates 3a-d were transformed into the desired targets 2a-d in seven steps. (C) 2000 Elsevier Science Ltd. All rights reserved.