In continuation of our previous study on the intramolecular reductive coupling of simple homoallylic esters promoted by allylSmBr/HMPA/H2O, which afforded a facile synthesis of 2-(2-hydroxyalkyl)cyclopropanols, here we report the reductive cascade cyclization of but-3-enyl but-3-enoates mediated by allylSmBr/HMPA/CuCl2·2H2O, in which the two C═C bonds were successively coupled to allow the construction of the structurally interesting bridged bicyclic tertiary alcohols. Thus, the 2-(2-hydroxyethyl)bicyclo[2.1.1]hexan-1-ols were prepared in moderate to good yields with excellent diastereoselectivity.
A variety of substituted quinoline/pyridine, thiochromene and naphthalene derivatives, which might be of biological and medicinal value, were synthesized by copper-catalyzed domino S N 2'/coupling, S N 2'/deacylation/coupling and S N 2'/coupling/elimination reactions. The method provides a general and convenient approach to the synthesis of various sub-stituted cyclic compounds from the corresponding Baylis-Hillman (B-H) acetates and N-/S-/C-nucleophiles.
The radical cyclization between aliphatic acyclic esters and alkenes was achieved unprecedentedly in the presence of allylsamarium bromide with HMPA and H(2)O as additives. The cascade radical cyclization-ring-opening-anionic cyclization allowed facile and efficient access to 2-(2-hydroxyalkyl)cyclopropanols from readily available materials.
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