Preparation and use of aziridino alcohols as promoters for the enantioselective addition of dialkylzinc reagents to N-(diphenylphosphinoyl) imines
Preparation and use of aziridino alcohols as promoters for the enantioselective addition of dialkylzinc reagents to N-(diphenylphosphinoyl) imines
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DOI：
10.1021/jo970918h
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发表时间：
1997-10-17
影响因子：
3.6
通讯作者：
Tanner, D
中科院分区：
文献类型：
--
作者：
Andersson, PG;Guijarro, D;Tanner, D
一组手性氮丙啶醇 2-5 已从容易获得的氨基酸（L-丝氨酸、L-苏氨酸和别-L-苏氨酸）或简单烯烃（使用 Sharpless 不对称氨基羟基化和二羟基化反应）开始合成。测试了手性配体2-5作为二烷基锌试剂与N-(二苯基膦酰基)亚胺1对映选择性加成的促进剂。研究了氮丙啶环和醇部分上的取代基对选择性的影响，在最好的情况下，可以获得高达94%的对映体过量。最初形成的N-保护胺6的酸水解产生相应的游离胺7，而没有外消旋化。尽管使用了化学计量的配体，但在后处理过程中可以回收约 90% 的配体并重新使用，而不会显着损失手性诱导。还评估了氮丙啶基醇 2-5 作为同一反应催化剂的效用，使用 0.25 当量的手性配体实现了高达 76% 的对映体过量。还提出了加成反应可能的过渡态。
A set of chiral aziridino alcohols 2-5 has been synthesized starting from either readily available amino acids (L-serine, L-threonine, and allo-L-threonine) or simple olefins (using Sharpless asymmetric aminohydroxylation and dihydroxylation reactions). Chiral ligands 2-5 have been tested as promoters for the enantioselective addition of dialkylzinc reagents to N-(diphenylphosphinoyl) imines 1. The influence of the substituents on the aziridine ring and the alcohol moiety on the selectivity has been studied, and in the best case, an enantiomeric excess of up to 94% could be obtained. Acidic hydrolysis of the initially formed N-protected amines 6 led to the corresponding free amines 7 without racemization. Although a stoichiometric amount of the ligand was used, about 90% of it could be recovered during the workup and reused without significant loss of chiral induction. The utility of the aziridino alcohols 2-5 as catalysts for the same reaction has also been evaluated and enantiomeric excesses of up to 76% were achieved using 0.25 equiv of the chiral ligand. A possible transition state for the addition reaction is also proposed.