We report an effective dynamic kineticresolution (DKR) system of racemic2-(1H-pyrrol-1-yl)alkanoic acids, which consists of a rapid racemization step via an activating substrate and an enantio-di...
METHOD FOR PRODUCING OPTICALLY ACTIVE CARBOXYLIC ACID ESTER
申请人:TOKYO UNIVERSITY OF SCIENCE FOUNDATION
公开号:US20170008820A1
公开(公告)日:2017-01-12
Provided is a method for producing an optically active carboxylic acid ester at a high yield and with high enantioselectivity using dynamic kinetic resolution, said optically active carboxylic acid ester having an α-nitrogen substituent. This method for producing an optically active carboxylic acid ester includes a step in which racemic carboxylic acid represented by formula (a) and a specific alcohol or phenol derivative are reacted in a polar solvent having a dipole moment of at least 3.5 in the presence of an acid anhydride and an asymmetric catalyst, one enantiomer of the racemic carboxylic acid is selectively esterified, and the other enantiomer is racemized. In formula (a), Ra1 represents a nitrogen-containing heteroaromatic ring group bonded to an assymetric carbon via a nitrogen atom constituting a ring, and Ra2 is an organic group.
A ruthenium complex with a monodentate phosphine ligand was used to catalytically hydrogenate N‐protected α‐aminoacids under essential retention of the configuration of their α‐chiral centers. Among the ligands tested for this hydrogenation, which proceeds at a relatively low temperature, tris(para‐fluorophenyl)phosphine exhibited the best performance. In comparison, electron‐rich monodentate, bidentate
具有单齿膦配体的钌配合物用于在N-保护的α-手性中心基本保留的条件下催化氢化N-保护的α-氨基酸。在进行这种氢化测试的配体中(在相对较低的温度下进行),三(对-氟苯基)膦表现出最好的性能。相比之下,富电子的单齿,双齿和三齿膦的效果要差得多。预催化剂Ru(OAc)2 [(p -FC 6 H 4)3 P] 2合成并分离,并通过单晶X射线衍射分析确定其结构。具有中性烷基侧链的N保护的α-氨基酸,包括硫化物,吲哚,醚,酚,吡咯和芳烃等极性官能团,与所应用的氢化条件兼容,从而提供了相应的旋光2取代2 (1 H-吡咯-1-基)乙-1-醇(2-氨基乙醇)衍生物,中等至高收率。
Pyrrole‐Protected β‐Aminoalkylzinc Reagents for the Enantioselective Synthesis of Amino‐Derivatives
作者:Marcel Leroux、Wan‐Yun Huang、Yannick Lemke、Thaddäus J. Koller、Konstantin Karaghiosoff、Paul Knochel
DOI:10.1002/chem.202000870
日期:2020.7.22
prepared starting from optically pure commercial β‐amino‐alcohols. These amino‐alcohols were converted to the corresponding N‐pyrrolyl‐protected alkyl iodides which undergo a zinc insertion in the presence of LiCl (THF, 25 °C, 10–90 min). Subsequent Negishi cross‐coupling or acylation reactions with acid chlorides produced amino‐derivatives with retention of chirality. Diastereoselective CBS‐reductions of
手性 β-氨基烷基卤化锌是从光学纯的商业 β-氨基醇开始制备的。这些氨基醇转化为相应的N-吡咯基保护的烷基碘,在 LiCl 存在下进行锌插入(THF,25 °C,10-90 分钟)。随后的根岸交叉偶联或与酰基氯的酰化反应产生了保留手性的氨基衍生物。一些制备的N-吡咯基酮的非对映选择性 CBS 还原提供了具有高非对映选择性的 1,3-取代的N-吡咯基醇。此外,涉及臭氧分解的脱保护程序可以将吡咯环转化为甲酰胺,而不会损失光学纯度。