Intramolecular Pauson–Khand reaction of optically active aza-Baylis–Hillman adducts

Ishikawa, Shingo; Noguchi, Fumiaki; Uno, Hidemitsu; Kamimura, Akio

doi:10.1016/j.tetlet.2010.02.115

Cited by 13 publications

(3 citation statements)

References 19 publications

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“…Optically active pyrrolidine ring-fused cyclopentenones 1184 have been obtained by Ishikawa et al by means of an intramolecular Pauson–Khand reaction starting from readily available optically active aza-Baylis–Hillman adducts 1182 (Scheme ). The PK precursors 1183 were prepared by S -oxidation of 1182 followed by propargylation of the resulting sulfonamines under basic conditions. The PKR conditions were optimized, and the bicyclic enones 1184 were isolated in excellent yields.…”

Section: Functionalization Of Chiral Building Blocksmentioning

confidence: 99%

Synthesis of Chiral Cyclopentenones

et al. 2016

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The cyclopentenone unit is a very powerful synthon for the synthesis of a variety of bioactive target molecules. This is due to the broad diversity of chemical modifications available for the enone structural motif. In particular, chiral cyclopentenones are important precursors in the asymmetric synthesis of target chiral molecules. This Review provides an overview of reported methods for enantioselective and asymmetric syntheses of cyclopentenones, including chemical and enzymatic resolution, asymmetric synthesis via Pauson-Khand reaction, Nazarov cyclization and organocatalyzed reactions, asymmetric functionalization of the existing cyclopentenone unit, and functionalization of chiral building blocks.

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Section: Functionalization Of Chiral Building Blocksmentioning

confidence: 99%

Synthesis of Chiral Cyclopentenones

et al. 2016

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“…This mild thiourea/Pd-catalyzed alkoxycarbonylative annulation has been used to synthesize other complex natural products, e.g., pallambins A and B by Carreira and Ebner, and pallambins C and D by Wong et al To build the highly substituted cyclopentenone moiety (F ring), we developed a novel thiourea/Co catalytic system to achieve the desired intramolecular [2 + 2 + 1] cycloaddition of an acetal-containing enyne precursor ( 25 → 26 , Figure B-2). Several other groups have used this catalytic version of the Pauson–Khand reaction for the total syntheses of natural products. − …”

Section: Retrosynthetic Analysis Of Schindilactone a And Two Enabling...mentioning

confidence: 99%

The Journey of Schinortriterpenoid Total Syntheses

Yang

2019

Acc. Chem. Res.

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CONSPECTUS: Plants in the Schisandraceae family are important components of the traditional Chinese herbal medicines and are often used to treat various illnesses. Therefore, these Schisandraceae plants are valuable sources for the discovery of new chemical entities for novel therapeutic development. Considerable progress has been made in the identification of bioactive and structurally novel triterpenoids from the Schisandraceae family in the past two decades. In particular, Sun and co-workers have successfully isolated over 100 nortriterpenoids from the Schisandraceae family. Some of these nortriterpenoids have strong inhibitory activities toward hepatitis, tumors, and HIV-1. However, the natural scarcity of these nortriterpenoids in the Schisandraceae plants has hampered their isolation and further biomedical development, and their biosynthesis has not been fully elucidated. It is therefore important and urgent to develop efficient and streamlined total syntheses of these medicinally important nortriterpenoids. Such syntheses will provide sufficient materials for detailed biological studies as well as new synthetic analogues and probe molecules to improve their biological functions and elucidate their mode of actions. However, because of their structural novelty and complexity, the total syntheses of these nortriterpenoid natural products present a significant challenge for synthetic chemists, despite the progress made in organic synthesis, particularly total synthesis, in the 20th century and since the beginning of the 21st century. New synthetic methodologies and strategies therefore need to be invented and developed to facilitate the total syntheses of these nortriterpenoid natural products. With this in mind, our group has spent the last 15 years, ever since the isolation of micrandilactone A (1) by Sun and co-workers in 2003 (Sun et al. Org. Lett. 2003, 5, 1023−1026, working on synthetic studies with a view to developing methods and strategies for the total syntheses of schinortriterpenoids. Enabling methods such as a thiourea/Pd-catalyzed alkocycarbonylative annulation and a thiourea/Co-catalyzed Pauson−Khand reaction have been developed under these circumstances to form the key ring systems and stereocenters of these complex target molecules. These methodological advances have led us to the first total syntheses of schindilactone A (2), lancifodilactone G acetate (6a), 19-dehydroxyarisandilactone A (9), and propindilactone G (10) with diverse structural features via a branchingoriented strategy. The chemistry developed during our total synthesis campaign has not only helped us to deal with various challenges encountered in the syntheses of the four target molecules, but has also opened up new avenues for synthesizing other naturally occurring schinortriterpenoids and their derivatives, which will likely result in molecules with improved biological functions and tool compounds to enable elucidation of their mechanism of actions or potential cellular targets. This Account highlights the chemistry evolutio...

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“…We have recently developed a facile method for the synthesis of enantiomerically enriched aza-Morita−Baylis−Hillman (aza-MBH) adducts, which are regarded as useful synthetic building blocks. 6 For example, we have employed the chiral N-allylic and N-propargylic β-amino-α-methylene esters for the synthesis of various heterocyclic compounds via the RCM reaction, 7 the Pauson-Khand reaction, 8 and the domino radical cyclization reaction. 9 A 1,6-enyne motif in the N-propargylic aza-MBH adducts prompted us to explore their potential as substrates in Au(I)-catalyzed reactions.…”

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confidence: 99%