A Modular Four-Component Route to Substituted 1,7,9-Decatrien-3-ones Using a Chloro-Substituted Phosphorane as Key C3 Building Block.

An efficient and flexible four-component route to substituted 1,7,9-decatrien-3-ones was established by alkylation of sodium dialkyl malonates with a chloro-substituted phosphorane followed by a Wittig reaction with the corresponding carbonyl compound. The resulting enones were alkylated at their malonate unit with sorbyl bromide to give the title compounds in good overall yields. In an attempt to improve the overall yield by using in situ generated sorbyl tosylate we discovered the formation of an unusual bicyclic product with a 3-oxocyclopenta[b]furan core that is formally generated by an oxidative dimerization of the employed precursor enone. The structure of this compound was unambiguously determined by an X-ray crystal analysis. [ABSTRACT FROM AUTHOR]