Anthony KERMAGORET - THESES ET MEMOIRES DE L'UDS

2. Results and Discussion
2.1 Synthesis of the ligands
Chapitre IV
The ligand 2-[(diphenylphosphino)methyl]pyridine 12 was prepared by deprotonation
of 2-methylpyridine with n-BuLi, followed by reaction with excess chlorotrimethylsilane at -
78 °C and reaction with 1 equivalent of chlorodiphenylphosphine at –78 °C. 52 This procedure
is crucial for a high yield synthesis of the corresponding ligand because the direct reaction of
the carbanion with PPh2Cl gives rise to byproducts. The ligand 2-[2-
(diphenylphosphino)ethyl]pyridine 13 was synthesized by reaction of 2-(pyridine)ethanol
with SOCl2 to give 2-chloroethylpyridine which was then reacted with NaPPh2. 53,54 The 1 H
NMR spectrum of 13 was analyzed using the MestRec software 55 by considering an
AA’BB’X spin system for the P-CH2 and Py-CH2 protons (Figure 1). The reaction of
(pyridin-2-yl)methanol with 1 equivalent of PPh2Cl or chloro(dibenzyl-1,2-oxa)phosphorine
in the presence of excess triethylamine (to neutralize the HCl liberated) afforded the new
ligands 2-methyl-oxy-(diphenylphosphino)pyridine 14 56 and 2-methyl-oxy(dibenzyl-1,2-oxa-
phosphorino)pyridine 15, respectively. Their properties are similar to those of their methyl
derivatives containing a POCMe2 instead of a POCH2 moiety. 50
Figure 1. 1 H NMR spectrum (300 MHz) of 13 showing the P-CH and the Py-CH protons.
2 2
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