Sonogashira double

Scheme 14 illustrates Linstrumelle s synthesis of (9Z,11 )-9,11,13-tetradeca-trienyl acetate (8), the pheromone of the pyralid moth, Stenoma cecropia [25]. The key steps were palladium and copper-catalyzed Sonogashira couplings (A+B and C+D). Another noteworthy feature in this synthesis was the use of activated zinc dust in aqueous methanol for the reduction of the triple bonds of E to give two double bonds of 8. 

The second example involves the synthesis of ortho-dipropynylated arenes (Scheme 4.12b), which serve as precursors to tribenzocyclyne by way of an alkyne metathesis reaction (see also Scheme 6.31). Here, a Sonogashira reaction was carried out in a pre-pressurized (propyne at ca. 2.5 bar) sealed microwave vessel in a standard single-mode microwave reactor. Double-Sonogashira coupling of the dibromodiiodo-benzene was completed within 20 min at 110 °C [30]. 

Scheme 6.31 Double Sonogashira reactions in pre-pressurized vessels.

Choudary, B.M., Madhi, S., Chowdari, N.S., Kantam, M.L. and Sreedhar, B., Layered double hydroxide supported nanopalladium catalyst for Heck-, Suzuki-, Sonogashira-, and Stille-type coupling reactions of chloroarenes, J. Am. Chem. Soc., 2002, 124, 14127-14136. 

Application of the Corey-Fuchs olefination to thioxanthone affords the 1,1-dibromoalkene 366 from which the 1,1-bis(trimethylsilylethynyl)alkene can be obtained by a double Sonogashira coupling reaction. Desilylation yields the 1,1-diethynylalkene (Scheme 86) <2004JA3108>. 

Sonogashira coupling of alkynes with 3-iodoflavones leads to 3-alkynylflavones and is best effected using (5)-prolinol it is successful in aqueous conditions <03T9563>. The ylide phenyliodonium )w(phenylsulfonyl)methylide inserts into the 2,3-double bond of flavones and offers a direct route to 3-substituted flavones <03T7929>. 

For the construction of the required acyclic enediyne, the method of choice is the Sonogashira coupling of terminal alkynes with Z dichloroethylene. The complete stereoselectivity for the Z double bond and the mild... 

Reaction of the enyne 129 with p-bromoanisole gave the furan 130 smoothly in 53 % yield via Sonogashira coupling and carbopalladation of the triple bond, followed by intramolecular insertion of the double bond (Heck-type reaction) [42],... 

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