Diels-Alder/thiol-olefin co-oxygenation approach to antimalarials incorporating the 2,3-dioxabicyclo[3.3.1]nonane pharmacophore
A Diels-Alder/thiol-olefin co-oxygenation approach to the synthesis of novel bicyclic endoperoxides 17a-22b is reported. Some of these endoperoxides (e.g., 17b, 19b, 22a and 22b) have potent nanomolar in vitro antimalarial activity equivalent to that of the synthetic antimalarial agent arteflene. Iron(II)-mediated degradation of sulfone-endoperoxide 19b and spin-trapping with TEMPO provide a spin-trapped adduct 25 indicative of the formation of a secondary carbon centered radical species 24. Reactive C-radical intermediates of this type may be involved in the expression of the antimalarial effect of these bicyclic endoperoxides.
O'Neill, Paul M.,Verissimo, Edite,Ward, Stephen A.,Davies, Jill,Korshin, Edward E.,Araujo, Nuna,Pugh, Matthew D.,Cristiano, M. Lurdes S.,Stocks, Paul A.,Bachi, Mario D.
p. 2991 - 2995
(2008/09/20)
Ring enlargement reaction of 2-(1-alkenyl)-1-cyclobutyl ketones. A new method for the preparation of 4-acyl-1-cyclohexenes
Various 1,2-disubstituted 4-acyl-1-cyclohexenes were obtained by the ethylaluminum dichloride promoted ring enlargement reaction of 2-(1-alkenyl)-1-cyclobutyl ketones prepared by the conjugate addition of 1-alkenylmagnesium bromides With 1-cyclobutenyl ketones.