手性芳基膦-噁唑啉的简便合成

膦-噁唑啉化合物作为一类“优势配体”,自发现以来就引起化学家们的广泛关注。 现有合成方法存在路线长、收率低、分离困难等问题。 本研究发展了一种合成手性芳基膦-噁唑啉(PHOX)的简单高效方法。 在1-羟基苯并三唑(HOBt)、1-(3-二甲氨基丙基)-3-乙基碳二亚胺盐酸盐(EDCI)作用下,2-(二苯基膦基)苯甲酸与多种光学纯的氨基醇发生缩合反应,高收率获得酰胺基醇类化合物;之后酰胺基醇经三苯基膦/三乙胺/四氯化碳体系处理完成噁唑啉环的构建,以64%86%的总收率得到膦-噁唑啉化合物。 随后,合成的化合物(S)-t-BuPHOX被应用于钯催化β-酮酯的脱羧Tsuji烯丙基化反应,得到了80%的收率和84%的ee值。 该新方法具有原料易得、条件温和、收率高等优点。

A Facile Synthesis of Chiral Phosphinoaryloxazolines

As a widely used class of privileged ligands, phosphinoaryloxazolines(PHOX) have attracted much attention from chemists. However, the previous synthetic methods have problems of long steps, low yield and difficult separation and so on. In this article, a simple and efficient procedure for the synthesis of phosphinoaryloxazolines(PHOX) has been developed. First, 2-(diphenylphosphino)benzoic acid was condensed with various enantiomerically pure amino alcohols in the presence of 1-hydroxylbenzotriazole(HOBt) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride(EDCI) in dimethylformamide to give the corresponding (amido alcohol)s amides in excellent yields. Then the (amido alcohol)s amides were subjected to the oxazoline ring formation by treatment with triphenylphosphine, triethylamine and carbon tetrachloride in acetonitrile to afford a series of phosphinooxazolines in 64%86% total yields. Subsequently, (S)-t-BuPHOX was applied in the palladium-catalyzed decarboxylative Tsuji allylations of β-ketoester, giving an excellent isolated yield of 80% with an enantiomeric excess of 84%. The new synthetic procedure has the advantages of using readily available starting materials, mild reaction conditions, and high overall yields.