Abstract For understanding the mechanism involved in the Wittigreaction, it is important to know the factors which influence the stability of 1,2-oxaphosphetane intermediates with pentacoordinate phosphorus; in these intermediates, the steric factor plays a predominant role. Studying the Wittigreaction between nonstabilized ylides and different aldehydes, we noted that the stereochemical outcome
Studies of Stereo-Selective Cyclo-Additions and Transformations of Substituted 2-Cyclopenten-1-one with Chiral Anthracene Templates.
作者:Weerachai Phutdhawong、Gedsirin Eksinitkun、Yonlada Jaroensuk、Anthony C. Willis、Waya S. Phutdhawong
DOI:10.13005/ojc/330601
日期:2017.12.28
The chiral (S)-9-(1-methoxyethyl), (R)-9-(1,2-dimethoxyethyl) and 9-(1R, 2R)-(1,2dimethoxypropyl) anthracenes were synthesised and used for the thermal Diels-Alder reaction with cyclopentene-3,5-dione. Unlike the maleic anhydride and N-substituted malemides, the cyclo-adducts were obtained with high regio-selectivity as a single diastereomer. The X-ray structure of the cyclo-adduct showed an enol form
合成了手性(S)-9-(1-甲氧基乙基),(R)-9-(1,2-二甲氧基乙基)和9-(1R,2R)-(1,2二甲氧基丙基)蒽,并将其用于热狄尔斯-与环戊烯-3,5-二酮的Al醛反应。与马来酸酐和N-取代的马来酰亚胺不同,以高区域选择性作为单个非对映异构体获得了环加合物。环加合物的X射线结构显示为烯醇形式,但13 C NMR显示两个环戊酮羰基的共振,表明溶液结构为二酮形式。使用羰基基团上的有机镁加成物进行的立体控制研究导致烯醇醚的水解裂解并消除了水,从而得到α-烷基酮蒽加合物。这些在制备手性环戊烯酮核心结构中没有成功。