title: Regioselective Transition-Metal-Free Allyl-Allyl Cross-Couplings.
abstract: Readily prepared allylic zinc halides undergo SN 2-type substitutions with allylic bromides in a 1:1 mixture of THF and DMPU providing 1,5-dienes regioselectively. The allylic zinc species reacts at the most branched end (γ-position) of the allylic system furnishing exclusively γ,α'-allyl-allyl cross-coupling products. Remarkably, the double bond stereochemistry of the allylic halide is maintained during the cross-coupling process. Also several functional groups (ester, nitrile) are tolerated. This cross-coupling of allylic zinc reagents can be extended to propargylic and benzylic halides. DFT calculations show the importance of lithium chloride in this substitution.
authors.affiliation: Ludwig-Maximilians-Universität München, Department Chemie, Butenandtstrasse 5-13, Haus F, 81377, München, Germany.
authors.forename: Mario
authors.initials: M
authors.lastname: Ellwart
authors.affiliation: Ludwig-Maximilians-Universität München, Department Chemie, Butenandtstrasse 5-13, Haus F, 81377, München, Germany.
authors.forename: Ilya S
authors.initials: IS
authors.lastname: Makarov
authors.affiliation: Ludwig-Maximilians-Universität München, Department Chemie, Butenandtstrasse 5-13, Haus F, 81377, München, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Achrainer
authors.affiliation: Ludwig-Maximilians-Universität München, Department Chemie, Butenandtstrasse 5-13, Haus F, 81377, München, Germany.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Zipse
authors.affiliation: Ludwig-Maximilians-Universität München, Department Chemie, Butenandtstrasse 5-13, Haus F, 81377, München, Germany. paul.knochel@cup.uni-muenchen.de.
authors.forename: Paul
authors.initials: P
authors.lastname: Knochel
keywords: 1,5-dienes; SN2 reaction; allylic compounds; cross-coupling; zinc