描述了一种涉及将大二硫醇内酯桥接到双环系统的新反应。制备了一系列大二内酯并将其转化为必需的大二硫代内酯。后一种底物通过暴露于萘化钠而被诱导跨大环桥接,从而在加入甲基碘后形成稳定的双环系统。通过除去硫,将如此获得的混合硫缩酮转化为许多饱和或不饱和双环或多环系统。桥接的立体化学遵循顺式和反式产物的相对能量,而不是大环的构象偏好。MM2 计算和 X 射线晶体结构测定证实了这一点
描述了一种涉及将大二硫醇内酯桥接到双环系统的新反应。制备了一系列大二内酯并将其转化为必需的大二硫代内酯。后一种底物通过暴露于萘化钠而被诱导跨大环桥接,从而在加入甲基碘后形成稳定的双环系统。通过除去硫,将如此获得的混合硫缩酮转化为许多饱和或不饱和双环或多环系统。桥接的立体化学遵循顺式和反式产物的相对能量,而不是大环的构象偏好。MM2 计算和 X 射线晶体结构测定证实了这一点
is commercially available, is a practical and useful Lewis acidcatalyst for acylation of alcohols with acidanhydrides or the esterification of alcohols by carboxylic acids in the presence of p-nitrobenzoic anhydrides. The remarkably high catalytic activity of scandium triflate can be used for assisting the acylation by acidanhydrides of not only primary alcohols but also sterically-hindered secondary
Vielgliedrige heterocyclische Verbindungen VIII. Zur Kenntnis der hochgliedrigen Mono- und Poly-lȧctonringe
作者:M. Stoll、A. Rouvé
DOI:10.1002/hlca.193501801153
日期:——
1. Es wurde gezeigt, dass die der Veresterungsreaktion entgegenlaufende Verseifungsreaktion keine messbare Geschwindigkeit besitzt.
1.《世界经济日报》,《世界经济日报》。
New and Efficient Method for the Preparation of Medium-sized Lactones from the Corresponding<i>ω</i>-Hydroxycarboxylic Acids
作者:Teruaki Mukaiyama、Jun Izumi、Isamu Shiina
DOI:10.1246/cl.1997.187
日期:1997.2
Medium-sized lactones are prepared in good yields on treating monomeric cyclic silyl siloxycarboxylates, prepared in situ from ω-hydroxycarboxylic acids and 1,2-bisdimethylsilylbenzene using RhCl(PPh3)3 catalyst, with an active catalyst of dimethylsilylbis(trifluoromethanesulfonate).
Facile Synthesis of Lactones from Silyl ω-Siloxycarboxylates Using<i>p</i>-Trifluoromethylbenzoic Anhydride and a Catalytic Amount of Active Lewis Acid
The lactonization of silyl ω-siloxycarboxylates is successfully carried out under mild conditions in good to high yields by using p-trifluoromethylbenzoic anhydride and a catalytic amount of active acidic species generated in situ from TiCl4 and AgClO4.