My PhD dissertation - Institut Fresnel

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A single-crystal X-ray analysis of pure (M)-(-)-44 (Figure 5) [197] revealed a
particular configuration of the ligand. Contrary to the alkyl chains in bisphosphine 43, the two
terminal methyl groups in the acetal chain of 44 are facing each other. The resulting torsional
angle θ (C1A-C6A-C7A-C8A) was found to be of 84.4 °.
Figure 5. Stereoscopic drawing of (M)-(-)-44.
Finally, dimethyl ether 41, derived from optically pure diol 39, was also converted to
its corresponding bis(diphenylphosphine) derivative 45 under the same conditions. This
bisphosphine only differs from its phenolic equivalent 42 by the additional carbon in the
hydrocarbon chain.
Br
Br
(P)-(-)-41
O
O
LiC(CH 3) (2.0 eq.)
THF, - 75 °C, 30 min
Li
Li
O
O
ClPPh 2 (2.0 eq.)
Tol., - 75 °C
Ph 2P
Ph 2P
O
O
(P)-(+)-45, 74%