[Mg].[CH:2](Br)=[CH2:3].[CH2:5]([O:21][CH2:22][CH:23]=[O:24])[CH2:6][CH2:7][CH2:8][CH2:9][CH2:10][CH2:11][CH2:12][CH2:13][CH2:14][CH2:15][CH2:16][CH2:17][CH2:18][CH2:19][CH3:20].Cl>O1CCCC1.BrC(Br)C.CCOCC>[CH2:5]([O:21][CH2:22][CH:23]([OH:24])[CH:2]=[CH2:3])[CH2:6][CH2:7][CH2:8][CH2:9][CH2:10][CH2:11][CH2:12][CH2:13][CH2:14][CH2:15][CH2:16][CH2:17][CH2:18][CH2:19][CH3:20]To a stirring mixture of 5.67 g of magnesium in 25 ml of tetrahydrofuran was added 10 drops of dibromoethane as an initiator. After the reaction began another 100 ml of tetrahydrofuran was added followed by the dropwise addition of a solution of 49.85 g of vinyl bromide in 250 ml of tetrahydrofuran at a rate to maintain reflux. After all of the magnesium had reacted, the solution was cooled to 0° C. and a solution of 44.2 g of (hexadecyloxy) acetaldehyde, prepared by the procedure of Example 3, in 175 ml of ether was added dropwise over 1/2 hour. After 1 hour at room temperature dilute hydrochloric acid was added. The tetrahydrofuran was removed and the residue was extracted with ether. The ether layer was washed with brine, dried and the solvent removed. The residue was purified by HPLC [hexane: ether (9:1), two columns, two passes] giving an oil which was distilled via a Kugelrohr apparatus (185°-190° C., 0.2 mm) giving a colorles oil which solidified on standing to give 20.17 g of the desired compound.
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