1,3-Dienyl thioethers

In this section, the preparation and reactivity of ce-lithiated dienyl and trienyl ethers as well as dienyl thioethers as acyl anion equivalents will be considered749-751. 

Addition of BuLi to a mixture of a 1,3-dienyl ether or -thioether (E- or Z-) and t-BuOK in THF at 50 °C results in an instantaneous, and essentially quantitative Demetallation. In the absence of /-BuOK butyllithium adds to the sulfides in a conjugate fashion [91]. a-Metallation of the oxygen-e thers also has been carried out with /-BuLi in THF [81] ... 

The 1-proton in 1,3-dienyl ethers and -thioethers is expected to be more acidic than that in vinyl ethers and vinyl sulfides, because the outer double bond is likely to exert some electron-withdrawing influence. However, addition of the base (in a conjugate fashion) will also be more facile than with the simple vinyl ethers and -thioethers. Reaction of 1-methylthio-l,3-butadiene with butyllithium or butyl-lithium. TMEDA in THF has been shown to result in conjugate addition [91]. The... 

Reaction of l-chloro-l-(phenylthio)alkanes with sodium dicarbonyl(cyclopenta-dienyl)ferrate provides (a-phenylthio)alkyliron complexes. If these complexes have a double bond in their side chain in an appropriate distance to the iron center, methylation of the thioether results in an intramolecular cyclopropanation via the corresponding sulfonium salt and the (alkylidene)iron complex as intermediates (Scheme 4—63). ... 

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