A mixture of 5 mmoles of the product from Step A and 11.0 mmoles of triphenylphosphine in 15 ml. of dimethylformamide is stirred and refluxed under nitrogen for 3 hours. The mixture is cooled and the phosphonium salt is collected on a filter. A mixture of 4 mmoles of the phosphonium salt, 100 ml. of ethanol, 1 ml. of acetone and 40 ml. of 0.3 N ethanolic lithium ethoxide is stirred at room temperature under nitrogen for 2 hours. Water (100 ml.) is added and the mixture is cooled in an ice-bath. The precipitate is collected and purified by chromatography on silica gel using 2% methanol in chloroform as the eluant to give 2-[3,5-di(2-methylallyl)phenyl]oxazolo[4,5-b]pyridine.
