Question

Conjugated linoleic acid methyl ester (CLA) is of interest biologically. Firstly, give a retrosynthetic analysis for this compound which uses the reagents provided. Then show the forward synthesis. Finally, how would you make phosphonium salt A? Mechanisms are not required in this answer but explain your chosen route in detail and highlight any aspects of selectivity. CO2Me CLA CO2Me Ph3P Ph3P Bro

Answer 1

Come corre - Ph : pha In wittig rearrangement lemeal phosphorus ylides phosphorus sreacts with an aldehyde (on ketone to gives a mixture of E and z-alkenes Stereochemistry of the arkene products are Contacled by the stereochanistry of the Betaine. The formation of alkene occursid via Sin elimination of oxophosphatane ܛܘܐ 1 . O alkine Anti OS

Addition of wiltig reagent to produce Syn and Atiti Betain intermediate The onti - Berani is more stable and produce a Anti Oxophosphatanc intermedi- ate finally decomposition of oxophaphat- are to gres Eralken Stable finally deomposition of abore compond giver E-alkene m ot Stepi mit phyfn ome zoalkone w an come prapy -coome Resonancely noha stabilized alkene Because the Sun betein intermede ate ylide giver gire a stable Z Sun-beroin.

syn -Beton to forms a Sun -oxophosphatare Intermediate which on deomposition to giver Z-olkomen heng Syn-oxophosphataine oome