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.
The synthesis of functionalised beta- and gamma-lactams by cyclisation of enamides using copper(I) or ruthenium(II) / Bryans, Js; Chessum, Nea; Parsons, Af; Ghelfi, Franco. - In: TETRAHEDRON LETTERS. - ISSN 0040-4039. - STAMPA. - 42:15(2001), pp. 2901-2905. [10.1016/S0040-4039(01)00320-3]
The synthesis of functionalised beta- and gamma-lactams by cyclisation of enamides using copper(I) or ruthenium(II)
GHELFI, Franco
2001
Abstract
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.
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