Acetic acid, 2-(triphenylphosphoranylidene)-, ethyl ester → (E)-5,5-bis(3-chlorophenyl)-2,4-pentadienoic acid ethyl ester

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Reaction Steps

In the manner described in Example 99, 3,3-bis(3-chlorophenyl)-2-propenal (14.6 g) was reacted with (carbethoxymethylene)triphenylphosphorane (19.15 g) in ethanol (50 ml) for 30 minutes at ambient temperature. The mixture of esters obtained from the usual work up was purified by HPLC (dichloromethanehexane; 1:2) to provide 3.2 g of the less polar (Z)-5,5-bis(3-chlorophenyl)-2,4-pentadienoic acid ethyl ester as an oil, and 11.2 g of (E)-5,5-bis(3-chlorophenyl)-2,4-pentadienoic acid ethyl ester. A portion of the (E)-isomer (E)-5,5-bis(3-chlorophenyl)-2,4-pentadienoic acid ethyl ester was crystallized from 2-propanol to give the ester, mp 68°-69° C. Anal. Calculated for C19H16Cl2O2 :C, 65.72; H, 4.64; Cl, 20.42 Found: C, 65.26; H, 5.09; Cl, 20.00.

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