Synthesis of Substituted 1,5-Dioxaspiro[2.4]heptanes from 2,3- Dichloroprop-1-ene

Organodilithium Intermediates as Useful Dianionic Synthons: Recent Advances

“…On the other hand, the methylenic homoallylic diols 162 led to the corresponding 1,6-dioxaspiro[3.4]octanes 164 upon treatment with iodine and silver(I) oxide in a mixture of dioxane/water as solvent (Scheme 37) [92]. Similarly, the DTBB catalyzed lithiation of 2,3-dichlopropene (166) in the presence of symmetrically substituted ketones led, after hydrolysis, to the corres-ponding methylene-substituted diols 167, which by treatment with sodium hydride and iodine in THF at 20ºC, furnished a series of 1,5-dioxaspiro[2.4]heptanes 168 (Scheme 38) [93]. This structural unit is present in many biologically active natural products.…”

1,3-Dilithio-2-(diphenylmethylene)propane

“…These compounds are appropriate precursors for dioxaspiroheptanones 3, which are present in many naturally occurring compounds. 7 The formation of compounds 2 would involve a dilithiated species of type 4.…”