The dienes 11–15 react with diphenylketene to give mixtures of the corresponding [2 + 2]-adducts 16–20 and [4 + 2]-adducts 21–25: the isomers 19/24 were converted into the optically active lactone 26 in two steps.
二烯11-15与二苯基
乙烯酮反应得到的混合物的相应的[2 + 2] -adducts 16-20和[4 + 2] -adducts 21-25:异构体19/24转化成光学活性内酯26在两步。