AbstractThe completely diastereoselective silyl triflate‐mediated methyl orthoformate alkylation of chiral N‐acyl‐4‐isopropyl‐1,3‐thiazolidine‐2‐thiones catalyzed by commercially available nickel(II) complexes is reported. The simple experimental procedure requires 2.5–5 mol% of bis(phosphine)nickel dichloride [(R3P)2NiCl2] complexes, proceeds under very mild conditions, and covers a wide array of acyl groups. Furthermore, it can potentially be expanded to different electrophiles.magnified image
describe the titanium tetrachloride-mediated reaction of chiral enolates derivedfrom thiazolidine thiones and non-enolizable imines. For example, N-(4-methoxyphenyl)ben- zaldimine (1) yields 2R,3S-(anti)-products with good selectivity, while N-benzyloxycarbonylbenzaldimine (2) equilibrates and sub- sequently eliminates benzyl alkoxide under the reaction conditions to produce 2R,3R-(syn)-isocyanates
不对称曼尼希缩合可以产生对映体纯的氨基羰基官能团,这是许多具有生物活性的天然产物和治疗剂的重要成分。我们描述了由噻唑烷硫酮和非烯醇化亚胺衍生的手性烯醇化物的四氯化钛介导的反应。例如,N-(4-甲氧基苯基)苯甲醛亚胺 (1) 以良好的选择性产生 2R,3S-(反)-产物,而 N-苄氧基羰基苯甲醛亚胺 (2) 在反应条件下平衡并随后消除苄基醇以优异的选择性生产 2R,3R-(syn)-异氰酸酯。通过简单地改变氮上的 Z 基团和反应条件,可以在操作上实现从反到顺的选择性逆转。