A stereoselective synthesis of trisubstituted alkenes. Part 2. The nickel-catalysed coupling of Grignard reagents with 6-alkyl-3,4-dihydro-2H-pyrans and acyclic enol ethers

Abstract

The Ni⁰-catalysed coupling of Grignard reagents devoid of β-hydrogens with 6-alkyl-3,4-dihydro-2H-pyrans and acyclic enol ethers is highly stereoselective and gives trisubstituted alkenes with retention of configuration. The reaction was applied to syntheses of the aggregation pheromone of the square-necked grain beetle, a fragment of Premonensin B, and the polyketide fragment of Jaspamide.