No abstract

[reaction: see text] A new method for the synthesis of 1,5-diynes, from the reaction of 1,3-dilithiopropyne and propargyl chlorides, was developed. This new methodology was used to prepare (4E,6Z,10Z)-4,6,10-hexadecatrien-1-ol, one of the pheromone components of the cocoa pod borer moth Conopomorpha cramerella, in 51% overall yield.

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Propargylation of alkyl halides: ( E )‐6,10‐dimethyl‐5,9‐undecadien‐1‐yne and ( E )‐7,11‐dimethyl‐6,10‐dodecadien‐2‐yn‐1‐ol product: (E)‐6,10‐dimethyl‐5,9‐undecadien‐1‐yne byproduct: 2‐butyn‐1‐ol product: (E)‐7,11‐dimethyl‐6,10‐dodecadien‐2‐yn‐1‐ol reactant: trimethylsilyl‐protected acetylene

Sequential treatment of 2,3-dichloropropene with magnesium and n-BuLi generates the operational equivalent of 1,3-dilithiopropyne, which upon treatment with aldehydes or ketones, produces the corresponding alkoxy lithium acetylide intermediates. Reaction of this alkoxide with tosyl chloride, and t-BuLi produces 1-substituted, or 1,1-disubstituted 1,3-enynes in a one-pot reaction. When this lithium acetylide intermediates, obtained by this procedure, were used to perform palladium-catalyzed cross-coupling reactions, followed by addition of thionyl chloride and pyridine, 1,4-disubstituted or 1,1,4-trisubstituted 1,3-enynes were obtained in a one-pot protocol.