My PhD dissertation - Institut Fresnel

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5 Conclusions and Outlook
Several fields of the phosphorus chemistry were studied, considering different
applications of organophosphorus compounds. First of all, new phosphine ligands have
been prepared by means of several different synthetic strategies. Achiral monodentate
tertiary phosphines were efficiently obtained, taking profit of organometallic techniques.
Several simple arylmetals generated by means of direct proton abstraction ("metalation")
or halogen/metal permutational exchange, have been treated with triethyl phosphites to
produce tertiary phosphines with excellent yields. Since this method proved to be
applicable to various structurally different substrates, more elaborated phosphines were
prepared by treatment of furyl or pyrrolyl derivatives. These phosphines could be used
for several types of cross coupling reactions and should widen the field of their
applications.
The field of asymmetric catalysis was also addressed by preparing chiral
bidentate phosphines. By successive halogen/lithium permutational exchanges on the
pivot starting substrate 2,2',6,6'-tetrabromobiphenyl, a panel of biphenylbisphosphines
was efficiently prepared in both enantiomerically pure forms. The method devised
allowed an important modularity of the ligands' structure, but also advantageously relied
on an early racemate resolution step. Furthermore, changing the biphenyl substitution
pattern permitted to vary the dihedral angle of the atropisomeric bisphosphines, which to
some extent can drastically increase the yields and selectivities of a catalytic reaction
process.
The generation of dilithiobiaryls to prepare a series of a biphenylbisphosphines
also gave the opportunity to determine their thermal and rotational stability. Biaryl
motifs are not only present in various chiral ligands but also in many natural products.
This observation made dilithiobiaryls very useful transient species since they can be
functionalized at will with different electrophiles. The crucial issue whether
enantiomerically pure dilithiobiphenyls could be generated and used without any loss of
their optical activity, was addressed. Dynamic NMR studies were conducted for two