Enantioselective sp<sup>3</sup> C–H alkylation of γ-butyrolactam by a chiral Ir(<scp>i</scp>) catalyst for the synthesis of 4-substituted γ-amino acids
作者:Yu-ki Tahara、Masamichi Michino、Mamoru Ito、Kyalo Stephen Kanyiva、Takanori Shibata
DOI:10.1039/c5cc07102j
日期:——
Ir-catalyzed sp3 C–H alkylation of γ-butyrolactam with alkenes was used for the highly enantioselective synthesis of 5-substituted γ-lactams, which were readily converted into chiral 4-substituted γ-amino acids.
This paper describes a new strategy for the stereoselective synthesis of pyrrolizidine and indolizidine based enamino esters and their acylderivatives from l-proline. The key reaction in this process involves deprotection followed by ring closure of cyclic N-Boc amino-β-ketoesters. Also, the synthesis of 5R,9R-(−)-indolizidine 209D has been accomplished using this protocol.
本文描述了一种新的策略,用于从1-脯氨酸立体选择性地合成吡咯烷和吲哚并立定的烯胺酯及其酰基衍生物。该过程中的关键反应包括脱保护,然后关闭环状N -Boc氨基-β-酮酸酯的环。同样,已经使用该方案完成了5 R,9 R -(-)-吲哚并立定209D的合成。
An asymmetric approach to the pyrrolizidine ring system via N-acetyl and N-propionyl anion cyclisation processes
作者:Anthony Murray、George R. Proctor、P.John Murray
DOI:10.1016/0040-4039(94)02233-2
日期:1995.1
An efficient route to the pyrrolizidineringsystem has been developed. The method, which uses N-acetyl and N-propionyl anion cyclisation reactions as the key steps has provided the natural pyrrolizidines (−)-(1R, 8S)-1-hydroxy-pyrrolizidine (10), (−)-pyrrolizidin-1-ene-3-one (13), (±)-trachelanthamidine (18) together with a range of 2-methyl substituted pyrrolizidine-3-ones.
that provides opticallyactive 2-substituted hexahydro-1H-pyrrolizin-3-ones in four steps from commercially available Boc (tert-but(oxy)carbonyl))-protected proline. Diastereoisomers (−)-11 and (−)-12 were assembled from the proline-derived aldehyde (−)-8 and ylide 9via a Wittig reaction and subsequent catalytichydrogenation (Scheme 3). Cleavage of the Boc protecting group under acidic conditions, followed
Asymmetric Baylis–Hillman reactions: catalysis using a chiral pyrrolizidine base
作者:Anthony G. M. Barrett、Andrew S. Cook、Akio Kamimura
DOI:10.1039/a806115g
日期:——
A novel chiral pyrrolizidine base 5 derived from L-proline promotes the BaylisâHillman reaction of ethyl and methyl vinyl ketones with electron deficient aromatic aldehydes with moderate levels of enantiomeric excess.