The distillate from sandalwood is one of the oldest and most highly valued fragrances in perfumery. The natural oil is in short supply and, until recently, synthetic substitutes have been difficult to prepare. Polysantol® (margin) is the most successful of these substitutes. Its synthesis in 1984 involved the aldol condensation shown below. 

(a) This synthetic step, although usable, had a significant drawback that was responsible for its modest yield (60%). Identify this problem in detail. 

(b) A solution that avoids conventional aldol condensation was published in 2004. A bromoketone is prepared and, upon reaction with Mg metal, gives a magnesium enolate. This enolate then reacts with the aldehyde selectively to give a hydroxyketone that may be dehydrated to the desired product. Discuss how this approach solves the problem outlined in part (a). 

Transcribed Image Text:

OH Polysantol