288374-65-2Relevant academic research and scientific papers
Pd-Catalyzed Decarboxylative Cycloaddition for the Synthesis of Highly Substituted δ-Lactones and Lactams
Shi, Linlin,He, Yingdong,Gong, Jianxian,Yang, Zhen
, p. 324 - 332 (2020/11/17)
An efficient palladium-catalyzed decarboxylative cycloaddition process of vinyl cyclic carbonates and vinyloxazolidinones for the synthesis of highly substituted δ-lactone and δ-lactam derivatives was developed. This protocol exhibits several unique characteristics, including broad substrate scope, good functional group tolerance, and operational convenience, which enables a regioselective access to a variety of lactone and lactam scaffolds in moderate to good yield. The redox-neutral catalytic system promotes formation of substituted scaffolds with in situ generation of a cyclic tetra-substituted double bond functionality.
Highly Diastereoselective Intramolecular Asymmetric Oxidopyrylium-olefin [5 + 2] Cycloaddition and Synthesis of 8-Oxabicyclo[3.2.1]oct-3-enone Containing Ring Systems
Ghosh, Arun K.,Yadav, Monika
, p. 8127 - 8142 (2021/06/21)
We have the investigated base mediated asymmetric intramolecular oxidopyrylium-alkene [5 + 2]-cycloaddition reaction which resulted in the synthesis of functionalized tricyclic ring systems containing an 8-oxabicyclo[3.2.1]octane core. Intramolecular cycloaddition constructed two new rings, three new stereogenic centers, and provided a tricyclic cycloadduct with high diastereoselectivity and isolated yield. We incorporated an α-chiral center and an alkoxy alkene tether on the substrates and examined the effect of the size of alkyl groups and alkene tether length on diastereoselectivity. The requisite substrates for the oxidopyrylium-alkene cycloaddition reaction were synthesized in a few steps involving alkylation of optically active α-hydroxy amide, furyllithium addition, reduction of resulting ketone, and Achmatowicz reaction followed by acylation of a lactol intermediate. We have proposed stereochemical models for the [5 + 2] cycloaddition reaction via the oxidopyrylium ylide. Interestingly, the alkoxy substituent on the stereocenter and the chain length are responsible for the degree of stereoselectivity of the cycloadduct.
Synthesis of Tridentate Chiral Spiro Aminophosphine?Oxazoline Ligands and Application to Asymmetric Hydrogenation of α-Keto Amides
Zhang, Feng-Hua,Wang, Chen,Xie, Jian-Hua,Zhou, Qi-Lin
, p. 2832 - 2835 (2019/04/13)
A new type of tridentate chiral spiro aminophosphine?oxazoline ligands (SpiroOAP) have been synthesized through four steps. The SpiroOAP ligands are highly efficient for the asymmetric hydrogenation of α-keto amides, providing a variety of synthetically useful α-hydroxy amides with excellent enantioselectivity (up to 98% ee) and turnover numbers (up to 10,000). (Figure presented.).
Synthesis of novel phase transfer catalysts derived from proline-mandelic acid/tartaric acid: their evaluation in enantioselective epoxidation and Darzen condensation
Mahajan, Deepak P,Godbole, Himanshu M,Singh, Girij P,Shenoy, Gautham G
, (2019/02/27)
Abstract : Herein, we have described the synthesis of novel chiral cyclic phase transfer catalysts (PTCs). These catalysts are synthesized from proline, mandelic acid and tartaric acid by using simple synthetic methods with competitive yields. These chira
Ru-catalyzed highly enantioselective hydrogenation of α-keto Weinreb amides
Zhao, Meng Meng,Li, Wan Fang,Ma, Xin,Fan, Wei Zheng,Tao, Xiao Ming,Li, Xiao Ming,Xie, Xiao Min,Zhang, Zhao Guo
, p. 342 - 348 (2013/07/26)
Asymmetric hydrogenation of α-keto Weinreb amides has been realized with [Ru((S)-Sunphos)(benzene)Cl]Cl as the catalyst and CeCl3· 7H2O as the additive. A series of enantiopure α-hydroxy Weinreb amides (up to 97% ee) have been obtained. Catalytic amount of CeCl 3·7H2O is essential for the high reactivity and enantioselectivity and the ratio of CeCl3·7H2O to [Ru((S)-Sunphos)(benzene)Cl]Cl plays an important role in the hydrogenation reaction.
An asymmetric, SmI2-mediated approach to γ-butyrolactones using a new, fluorous-tagged auxiliary
Vogel, Johannes C.,Butler, Rebecca,Procter, David J.
experimental part, p. 11876 - 11883 (2009/04/06)
A new, fluorous-tagged chiral auxiliary has been developed for the asymmetric, SmI2-mediated coupling of aldehydes and α,β-unsaturated esters. γ-Butyrolactones are obtained in moderate to good isolated yield and in high enantiomeric excess. The fluorous tag allows the auxiliary to be conveniently recovered by fluorous solid-phase extraction (FSPE) and reused.
Synthesis of 1-aza-cryptophycin 1, an unstable cryptophycin. An unusual skeletal rearrangement
Barrow, Russell A.,Moore, Richard E.,Li, Lian-Hai,Tius, Marcus A.
, p. 3339 - 3351 (2007/10/03)
A total synthesis of cryptophycin 337 (1-aza-cryptophycin 1, 2), an analogue of the potent antitumor antibiotic cryptophycin 1 (1), is described. Cryptophycin 337 was unstable and underwent an unexpected skeletal rearrangement. (R)-Mandelic acid was used as the sole source of asymmetry for the synthesis of unit A. (C) 2000 Elsevier Science Ltd.
