Stereoselective synthesis of 4-hydroxy-2-phenylproline framework
摘要:
Highly diastercoselective (>20:1) bromo-lactonization of N-sulfonyl-2-allyl-2-phenylglycine methyl ester (11) was observed. Successive treatment of the chiral lactone with MeONa gave the desired (2S,4R)-4-hydroxy-2-phenylproline derivative in high yield without erosion of the diastereoselectivity. The starting chiral non-racemic compound (5) was prepared from the racemic 2-phenylglycine using a classical kinetic resolution (crystallization), an asymmetric phase transfer alkylation, and an enzyme-catalyzed kinetic resolution. (C) 2005 Elsevier Ltd. All rights reserved.
zed asymmetric SNAr reactions provide unique contribution to the catalyticasymmetric α‐arylations of carbonyl compounds to produce biologically active α‐aryl carbonyl compounds, the electrophiles were limited to arenes bearing strong electron‐withdrawing groups, such as a nitro group. To overcome this limitation, we examined the asymmetric SNAr reactions of α‐amino acid derivatives with arene chromium
尽管相转移催化的不对称S N Ar反应为羰基化合物的催化不对称α-芳基化反应产生了生物活性的α-芳基羰基化合物做出了独特贡献,但亲电试剂仅限于带有强吸电子基团的芳烃,例如硝基。为了克服这一局限性,我们研究了α-氨基酸衍生物与衍生自氟代芳烃的芳烃铬配合物(包括含给电子取代基的芳烃铬配合物)的不对称S N Ar反应。联萘改性的手性相转移催化剂可有效地促进芳基化反应,从而生成相应的α,α-二取代的α-氨基酸,其中包含具有高对映选择性的各种芳族取代基。
Stereoselective synthesis of 4-hydroxy-2-phenylproline framework
作者:Kenji Maeda、Ross A. Miller、Ronald H. Szumigala、Ali Shafiee、Sandor Karady、Joseph D. Armstrong
DOI:10.1016/j.tetlet.2004.12.130
日期:2005.2
Highly diastercoselective (>20:1) bromo-lactonization of N-sulfonyl-2-allyl-2-phenylglycine methyl ester (11) was observed. Successive treatment of the chiral lactone with MeONa gave the desired (2S,4R)-4-hydroxy-2-phenylproline derivative in high yield without erosion of the diastereoselectivity. The starting chiral non-racemic compound (5) was prepared from the racemic 2-phenylglycine using a classical kinetic resolution (crystallization), an asymmetric phase transfer alkylation, and an enzyme-catalyzed kinetic resolution. (C) 2005 Elsevier Ltd. All rights reserved.
Advantage of Anaerobic Conditions in the Highly Enantioselective Synthesis of α,α-Dialkyl-α-Amino Acids by Chiral Phase-Transfer Catalysis
Intervention of the enolate oxidation in the catalytic asymmetric phase-transfer alkylation of protected α-amino acid derivatives under aerobic conditions has been addressed, and anaerobic conditions have been introduced to obtain synthetically satisfactory chemical yields as well as a high level of enantioselectivity.