Synthesis and properties of a sterically crowded triarylphosphine bearing an ester group

A sterically crowded triarylphosphine bearing an ester group, (4-ethoxycarbonyl-2,6-diisopropylphenyl)bis(2,4,6-triisopropylphenyl)phosphine, was synthesized by the lithiation of the corresponding (bromoaryl)phosphine followed by the reaction with excess diethyl carbonate. The ester was obtained as lemon yellow crystals and exhibits the blueshifted UV-Vis absorption and fluorescence as compared with the orange-colored corresponding aldehyde and ketone. The effect of the substitution of an ester group on the photophysical and redox properties of the sterically crowded triarylphosphine is discussed, and the properties of the sterically crowded triarylphosphines bearing an aldehyde, a ketone, and an ester groups are briefly reviewed.