Stereocontrolled N-acyliminium ion cyclisation of L-DOPA derived succinimide 5 has been investigated. Addition of organolithiums to chiral non-racemic 5 yields oxoamides, which are cyclised diastereoselectively upon treatment with BF3-OEt2, to afford 5,10b-trans pyrroloisoquinolones in moderate yields and high ee (99%). (C) 2001 Elsevier Science Ltd. All rights reserved.