orthoesters 14–22 were prepared by an exchange reaction with orthoester 13. These compounds, after treatment with trimethylsilytriflate or tin(IV) chloride, gave rise to vinyl dioxolanylium cations which proved to be very reactive dienophiles in various Diels-Alder reactions.
手性原酸酯14-22通过与原酸酯13的交换反应制备。用三甲基甲
硅烷基
三氟甲磺酸盐或
氯化锡(IV)处理后,这些化合物产生了
乙烯基二氧杂
萘鎓阳离子,在各种狄尔斯-阿尔德反应中,
乙烯基二氧杂
环戊烯鎓阳离子被证明是非常活泼的亲二烯体。