The synthesis of functionalised beta- and gamma-lactams by cyclisation of enamides using copper(I) or ruthenium(II)

Cyclisation of a variety of halo-enamides with copper(I) or ruthenium(II) complexes has been investigated. The regioselectivity of the radical cyclisation, which can proceed via either a 4-exo or 5-endo pathway, to form beta- or gamma -lactam products respectively, is determined by the nature of the metal oxidant and the reaction conditions. Thus, whereas copper(I)bipyridine reactions give predominantly gamma -lactams, the use of copper(I)/TMEDA or dichlorotris(triphenylphosphine)ruthenium(II) affords mainly beta -lactams. (C) 2001 Elsevier Science Ltd. All rights reserved