Chirality transfer during cyclobutyl-cyclopropylmethyl-homoallyl cation rearrangement and synthesis of (-)-eldanolide.
The (3R)-2,2-dimethyl-3-(2-methoxycarbonyl)ethylcyclobutyl cation rearranged to give (1S,2S)-1-(1-methoxy-1-methyl)ethyl-2-(2-methoxycarbonyl)ethylcyclopropane. The latter was transformed into (4R)-4-(3-methylbut-2-enyl)-4-butyrolactone with a high degree of chirality transfer. The γ-lactone was converted into (−)-eldanolide, an antipode of the wing gland pheromone of an African sugar-cane borer.