Synthesis of optically active heterocyclic compounds via deracemization of 1,2-diol monotosylate derivatives bearing a long aliphatic chain by a combination of enzymatic hydrolysis with Mitsunobu inversion
摘要:
We have succeeded in accomplishing the deracemization of (+/-)-2-acetoxydecyl and (+/-)-acetoxy-6-benzyloxyhexyl tosylates, which have a long substituent, via an enzyme-mediated enantioselective hydrolysis with a Mitsunobu inversion using polymer-supported triphenylphosphine to afford the corresponding (S)-enantiomer. Enantiomerically pure (S)- and (R)-gamma-dodecalactones, a fruit flavor, were synthesized from (S)-2-acetoxydecyl tosylate as the mutual starting material. The poisonous alkaloid (S)-coniine was also synthesized using enantiomerically pure allyl amine as the key intermediate derived from (S)-acetoxy-6-benzyloxyhexyl tosylate. (C) 2012 Elsevier Ltd. All rights reserved.
Asymmetric hydrolytic kinetic resolution with recyclable polymeric Co(<scp>iii</scp>)–salen complexes: a practical strategy in the preparation of (S)-metoprolol, (S)-toliprolol and (S)-alprenolol: computational rationale for enantioselectivity
作者:Tamal Roy、Sunirmal Barik、Manish Kumar、Rukhsana I. Kureshy、Bishwajit Ganguly、Noor-ul H. Khan、Sayed H. R. Abdi、Hari C. Bajaj
DOI:10.1039/c4cy00594e
日期:——
epoxide (up to 46% compared to 50% theoretical yield) along with high enantioselectivity (up to 99%) were obtained in most cases using catalyst 1. Further studies showed that catalyst 1 could retain its catalyticactivity for six cycles under the present reaction conditions without any significant loss in activity or enantioselectivity. To show the practical applicability of the above synthesized catalyst
An Efficient Catalytic Asymmetric Epoxidation Method
作者:Zhi-Xian Wang、Yong Tu、Michael Frohn、Jian-Rong Zhang、Yian Shi
DOI:10.1021/ja972272g
日期:1997.11.1
This article describes a highly effective catalyticasymmetricepoxidation method for olefins using potassium peroxomonosulfate (Oxone, Dupont) as oxidant and a fructose-derived ketone (1) as catalyst. High enantioselectivies have been obtained for trans-disubstituted and trisubstituted olefins which can bear functional groups such as tributylsilyl ether, acetal, chloride, and ester. The enantiomeric
Collaborative effect of Mn-porphyrin and mesoporous SBA-15 in the enantioselective epoxidation of olefins with oxygen
作者:Kayhaneh Berijani、Hassan Hosseini-Monfared
DOI:10.1016/j.ica.2017.10.037
日期:2018.2
rational design of heterogeneous, low cost transition metal complexes that can catalyze olefin with high enantioselectivity and activity has been a challenging goal for the synthetic chemist. In this study a chiral ion pair strategy was used for the synthesis of a biomimetic efficient manganese-tetrapyridylporphyrin (H2TPyP) catalyst for the asymmetric epoxidation of olefins with O2. Complex Mn-TPyP
synthesized using cis-1-amino-2-indanol substituent. It showed remarkable catalytic activity and enantioselectivity in the epoxidation of olefins with O2/RCHO. Terminal olefins and styrene derivatives were successfully oxidized (> 99% ee). TON of 73,000 was achieved in the epoxidation of α-methylstyrene after five times recycling.Graphical Abstract
selectivity in the epoxidation of olefins with oxygen in the presence of isobutyraldehyde under mild conditions (conversion 38–98%; selectivity 65–98%; and enantioselectivity 58–100%, except for alpha-methylstyrene). Furthermore, the synergistic effect of the reduced graphene oxide support was observed on the increasing activity, epoxide selectivity, and enantioselectivity. The catalyst can be recovered
在此,通过将复合物[Mn(L)(OH)]接枝到碳包覆的磁性Fe 3 O 4纳米粒子修饰的还原氧化石墨烯上,合成了一种新型的非均相手性催化剂,GFC- [Mn(L)(OH)]。胺键(L =(1R,2S)-1-(N-水杨亚氨基)-2-茚满醇)形成的薄板(GFC )。催化剂通过FT-IR,UV / vis,XRD,SEM和振动样品磁力计(VSM)技术。在温和的条件下,在异丁醛存在下,烯烃与氧气的环氧化反应中表现出出色的活性和选择性(转化率38-98%;选择性65-98%;对映选择性58-100%,α-甲基苯乙烯除外)。此外,观察到还原的氧化石墨烯载体对增加的活性,环氧化物选择性和对映选择性的协同作用。该催化剂可以回收通过从反应混合物中进行磁分离,并循环五次,而其活性没有任何重大损失。这种发展的优点是利用还原的氧化石墨烯和磁铁矿纳米颗粒的协同作用来获得易于回收的非均质绿色催化剂。另外,对配体的基于