Vinylic Organoboranes. 3. Pheromones via Organoboranes. 1. Stereospecific Synthesis of Straight-Chain Z-Monoolefinic Insect Pheromones via Lithium (1-Alkynyl)trialkylborates

Article abstract of DOI:10.1021/jo00374a004

Various insect pheromones with straight-chain Z-monoolefinic structures have been prepared from lithium (1-alkynyl)trialkylborates.Treatment of lithium (1-alkynyl)trialkylborates, readily prepared from lithium acetylides and trialkylboranes, with iodine under mild conditions produces the corresponding alkynes in essentially quantitative yield.Monohydroboration of the resultant alkyne with 9-borabicyclo<3.3.1>nonane yields the corresponding (Z)-olefin after protonolysis.The combination of these two reaction sequences provides a general route for the synthesis of (Z)-olefins.The position of the double bond and the carbon-chain length are easily controlled by properly choosing the initial reactants.The incorporation of functional groups is also easily achieved because of the mild reaction conditions and the tolerance of hydroboration to many functional groups.High yield and purity of the products are obtained.