Tackling the Spiro Tetracyclic Skeleton of Cyanogramide: Incorporation of a Hydantoin Moiety
作者:Marco Monecke、Thomas Lindel
DOI:10.1021/acs.orglett.8b03540
日期:2018.12.21
Wang’s enantioselective thiourea-catalyzed spiro-annulation paved the way to the first tetracyclic analog of the marine natural product cyanogramide from the actinobacterium Actinoalloteichus cyanogriseus. The synthesis comprises seven steps starting from an alkylidene indolinone. Installation of the (E)-styryl side chain faced a regiochemistry problem, circumvented by prior conversion to the hydantoin
Wang的对映选择性硫脲催化的螺旋环化为放线菌Actinoalloteichus cyanogriseus的海洋天然产物氰化物的第一个四环类似物铺平了道路。所述合成包括从亚烷基吲哚酮开始的七个步骤。(E)-苯乙烯基侧链的安装面临区域化学问题,这是通过事先转化为乙内酰脲并采用巴蒂条件来避免的。螺二氢吲哚吡咯并[1,2- c ]咪唑和氰化物的ECD光谱比较证实了天然产物的绝对构型。
Phosphine-Catalyzed Synthesis of 1,3-Dioxan-4-ylidenes
作者:Xue-Feng Zhu、Christopher E. Henry、Jay Wang、Travis Dudding、Ohyun Kwon
DOI:10.1021/ol050203y
日期:2005.3.1
A phosphine-catalyzed reaction of an allenoate with aldehydes furnished (2,6-diaryl-[1,3]dioxan-4-ylidene)-acetates 4 in excellent to moderate yields with complete diastereoselectivity and high E/Z-selectivities. Upon removal of the acetal functionality in this domino reaction product 4, delta-hydroxy-beta-ketoester 11 was obtained. The reported vinylphosphonium-based approach provides a new way to achieve a synthesis of 6-hydroxy-beta-ketoesters that differs from the classical dianion-based approach.