Chemistry Reference
In-Depth Information
8B
ENANTIOSELECTIVE ALLYLIC
SUBSTITUTIONS WITH CARBON
NUCLEOPHILES
G Ü NTER HELMCHEN
Organisch - Chemisches Institut der Universit ä t Heidelberg, D - 69120 Heidelberg,
Germany
ULI KAZMAIER
Institut f ü r Organische Chemie, Universit ä t des Saarlandes, D - 66123 Saarbr ü cken,
Germany
SEBASTIAN F Ö RSTER
Organisch - Chemisches Institut der Universit ä t Heidelberg, D - 69120 Heidelberg,
Germany
8B.1. INTRODUCTION AND SCOPE
The metal-catalyzed allylic substitution is an important tool in organic synthesis. It is
schematically described in Scheme 8B.1. The reaction can be carried out with a variety of
transition metals, substitution patterns of the allylic moiety, and nucleophiles in stoichio-
metric or catalytic fashion. Furthermore, addition of a nucleophile can occur at a terminal
or the central carbon. The latter reaction mode is rare for palladium, however, very
common for other metals. Mechanistic understanding of the reaction requires thorough
knowledge of the properties of
-allyl metal complexes and their interconversion.
The early work in this fi eld centered on palladium. Smidt and Hafner [1], famous for
their invention of the Wacker process (1956), reported the fi rst (
π
- and
σ
- allyl)Pd complex in
1959. The possibility of a C
-C bond-forming substitution reaction with (
π
- allyl)Pd com-
plexes was discovered by Tsuji et al. in 1965, then an industrial chemist at Toray Indus-
tries [2]. Important improvements are due to other industrial chemists (Toray Industries,
π
