My PhD dissertation - Institut Fresnel

1 Introduction
1
The present thesis work aims at linking organophosphorus chemistry and modern
organometallic techniques. Thus, phosphorus compounds will not only serve as targets of
synthesis obtained through organometallic methods, but also as probes for gaining better
insight into organometallic reactivity. One main objective is the preparation of new phosphine
ligands for transition-metal-catalyzed reactions. In the course of this work, thermodynamical
investigations will also be performed in order to assess the rotational stability of some
atropisomeric biphenyl substrates. On the other hand, tetraalkylphosphonium salt will serve as
a substrate for alkaline decomposition, allowing us to compare relative basicities of various
alkyl anions.
1.1 Atropisomerism and Axially Chiral Bisphosphine
Ligands
The biphenyl core belongs to the classical examples of so-called atropisomerism, a
particular case of axial chirality. This type of enantiomerism was first demonstrated in 1922
by G.H. Christie and J. Kenner
"atropisomerism" was later coined by R. Kuhn
[ ] 1 when they resolved 6,6'-dinitro-2,2'-diphenic acid. The term
[ ] 2 referring to the restricted rotation about the
pivot sp 2 -sp 2 single bond (from Greek, a meaning not, and tropos meaning turn).
O2N HOOC
COOH
NO2 HOOC NO2 O2N COOH
(M) atropisomer mirror plane (P) atropisomer
Biaryls have a "chiral axis" and can be isolated in two nonplanar enantiomeric forms,
provided that their helicity is maintained by hampered rotation about the aryl-aryl bond.