Stereoselective Synthesis of Highly Substituted Annulated Dihydropyrans Based on γ-Lithiation and Homoaldol Reaction of an Enantiopure α-Silylated Vinyl Carbamate
作者:Dieter Hoppe、Thérèse Hémery、Birgit Wibbeling、Roland Fröhlich
DOI:10.1055/s-0029-1218596
日期:2010.1
is converted into the corresponding [1-(trimethylsilyl)vinyl] carbamate. Its γ-lithiation by means of sec-butyllithium/TMEDA, titanation, and addition to aldehydes leads with high stereoselectivity to enantiopure anti-homoaldol products. These add, under the influence of boron trifluoride-diethyl ether complex, a second equivalent of aldehyde and form, in an intermolecular silyl-Prins reaction, the
(-)-肉豆蔻醇的N,N-二异丙基氨基甲酸酯转化为相应的[1-(三甲基甲硅烷基)乙烯基]氨基甲酸酯。通过仲丁基锂/ TMEDA的钛化,钛化以及醛的加成,使得对映体纯的抗高碘醇产品具有很高的立体选择性。它们在三氟化硼-乙醚络合物的作用下添加第二当量的醛,并在分子间甲硅烷基-Prins反应中形成标题化合物,再次具有基本完全的立体选择性。脱甲硅烷基化后,反应按照规则的过程进行,形成了一个环状的五元环。 手性烯丙基氨基甲酸酯-氨基甲酸乙烯酯-非对映选择性γ-锂化-醛加成-环二氢吡喃