Iron-Catalyzed Regio- and Stereoselective Carbolithiation of Alkynes

Abstract

Butylation problems ironed out: 3-Pentynyl ethers react with butyllithium at -20°C in toluene, upon addition of a catalytic amount of a cheap iron(III) salt, to afford (E)-4-methyl-3-octenyl ethers in high yields. Stereochemically defined tetrasubstituted alkenes were also obtained by the subsequent addition of electrophiles (E⁺ , see scheme; acac = acetylacetonate, Bn=benzyl).