First Use of Axially Chiral Thioamides for the Stereocontrol of C−C Bond Formation
作者:Shubhada Dantale、Vincent Reboul、Patrick Metzner、Christian Philouze
DOI:10.1002/1521-3765(20020201)8:3<632::aid-chem632>3.0.co;2-x
日期:2002.2.1
first time, these atropisomeric thioamides were used for an asymmetric Claisen rearrangement. LDA deprotonation led selectively to the enethiolates of Z stereochemistry, and subsequent reaction with a variety of allyl halides furnished S-allyl keteneaminothioacetals. These intermediates were not detected as they rearranged readily to gamma-unsaturated thioamides in good to high yields and diastereoselectivities
制备了几种具有沿NC(芳基)键的手性轴的N-芳基取代的硫代酰胺,收率良好至优异。NMR光谱显示偏爱E旋转异构体(沿着NC(= S)键)。X射线晶体学分析表明,芳基和硫代酰胺基团的平面几乎垂直(79度)。这些阻转异构的硫代酰胺首次用于不对称的克莱森重排。LDA的去质子化选择性导致Z立体化学的烯硫醇化物,随后与各种烯丙基卤的反应提供了S-烯丙基烯酮氨基硫缩醛。未检测到这些中间体,因为它们以高至高收率和高达88:12的非对映选择性重排为γ-不饱和硫酰胺。化学相关性允许分配(aR *,2R *)构型为主要的非对映异构体。提出了一个模型来解释硫代克莱森重排的立体化学过程。