Nitroso-ene cyclization enabled access to 1-azaspiro[4.4]nonane and its application in a modular synthesis toward (±)-cephalotaxine

Huang, Sha‐Hua; Tian, Xiaoping; Mi, Xianwei; Wang, Yan; Hong, Ran

doi:10.1016/j.tetlet.2015.10.002

Cited by 29 publications

(5 citation statements)

References 51 publications

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“…Further examples of the valuable application of the thermolysis of the HDA cycloadducts come from the use of the stable hydroxamic acid 2ef in the synthesis of 9,10-DMA cycloadduct followed by thermal-promoted ene reaction to give the 6-endo product 319a and the 5-exo product 319b in >90% yields and 9:1 endo/exo ratio (Scheme ). The major product of this reaction was the key starting material for the first total synthesis of (−)-hosieine A …”

Section: Nitrosocarbonyl Generation Methodsmentioning

confidence: 99%

Generation and Trapping of Nitrosocarbonyl Intermediates

Memeo

Quadrelli

2017

Chem. Rev.

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The nitrosocarbonyls (R-CONO) are highly reactive species and remarkable intermediates toward different synthetic targets. This review will cover a research area whose impact in current organic synthesis is constantly increasing in the chemical community. This review represents the first and comprehensive picture on the generation and trapping of nitrosocarbonyls and is solidly built on more than 380 papers. Six different classes of key starting materials such as hydroxamic acids, N-hydroxy carbamates, N-hydroxyureas, nitrile oxides, and 1,2,4-oxadiazole-4-oxides were highlighted. The content of the review surveys all the methods to generate the nitrosocarbonyls through different approaches (oxidative, thermal, photochemical, catalytic, aerobic, and the less common ones) in the light of efficiency, yields, and mildness. The most successful trapping agents employed to catch these fleeting intermediates are reviewed, exploiting their superior dienophilic, enophilic, and electrophilic power. The work is completed by paragraphs dedicated to the detection of the intermediates, theoretical studies, and insights about the challenges and future directions for the field.

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Section: Nitrosocarbonyl Generation Methodsmentioning

confidence: 99%

Generation and Trapping of Nitrosocarbonyl Intermediates

Memeo

Quadrelli

2017

Chem. Rev.

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“…workers' application of the nitroso-ene reaction to construct 6-azaspiro [4.5]decane under direct oxidation conditions, 20 we envisioned that 1-azaspiro [4.4]nonane (module B) should be readily prepared through the nitroso-ene reaction. 21 The synthesis began with the ring-opening reaction of commercially available 1,2-epoxycyclopentane 7 through an in situ generated dimethylsulfonium methylide (Scheme 4). The resulting volatile allylic alcohol was directly subjected to the Johnson-Claisen rearrangement to furnish ethyl 3-(cyclopenten-1-yl)propanoate (8).…”

Section: Syn Lettmentioning

confidence: 99%

“…Only 10% of the reducing product 44 was isolated, and the reproducibility was problematic. Therefore, using the same procedure as that utilized in the formal synthesis of cephalotaxine, 21 acetylation and SmI 2 -promoted reduction resulted in the lactam 44 in 65% yield in two steps (Scheme 11, a). The following N-methylation with methyl iodide proceeded smoothly to afford 45 in 93% yield.…”

Section: Account Syn Lettmentioning

confidence: 99%

Crossing the Ring: A Journey of the Nitroso-ene Reaction

Ouyang

Wang

et al. 2017

Synlett

Self Cite

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Recent progress in the nitroso-ene reaction indicates the potentially rich reactivity of the nitroso species. In this study, we highlight the synthetic efforts towards the construction of the aza-spirocyclic or aza-bridged ring embedded in biologically significant alkaloids via the proposed approach. Our endeavors along this direction are exemplified in the formal synthesis of (±)-cephalotaxine and the total synthesis of (-)-hosieine A. 1 Introduction 2 Aza-Spirocyclane: A Formal Synthesis of (±)-Cephalotaxine 3Method Development 4Aza-Bridge Ring: A Total Synthesis of (-)-Hosieine A 5 Epilogue

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“…Moreover, several studies on cyclopentene epoxidation have also been reported (Hulea et al, 1998;Kluson et al, 2005). The main product of cyclopentene epoxidation is 1,2-epoxycyclopentane (CPO), which is widely used as the intermediate in medicine and organic synthesis (Milen et al, 2000;Huang et al, 2015;Seol et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Modified Ti-MWW Zeolite as a Highly Efficient Catalyst for the Cyclopentene Epoxidation Reaction

et al. 2020

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The liquid-phase epoxidation of cyclopentene (CPE) was performed in the Ti-zeolite/H 2 O 2 catalytic system for the clean synthesis of cyclopentene oxide. Among all the Ti-zeolites (Ti-Beta, Ti-MOR, Ti-MCM-68, TS-1, TS-2, and Ti-MWW) investigated in the present study, Ti-MWW provided relatively lower CPE conversion of 13% due to the diffusion constrains but a higher CPO selectivity of 99.5%. The catalytic performance of Ti-MWW was significantly enhanced by piperidine (PI) treatment, with the CPE conversion and CPO selectivity increased to 97.8 and 99.9%, respectively. The structural rearrangement upon PI treatment converted the 3-dimensional (3D) MWW structure to a 2D lamellar one, which enlarged the interlayer space and greatly alleviated the diffusion constrains of cyclic cyclopentene. Furthermore, the newly constructed "open site" six-coordinated Ti active sites with PI as the ligand exhibited higher catalytic activity. The two factors contributed to more significant enhancement of the activity upon PI-assisted structural arrangement compared to the cases in linear alkenes.

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Nitroso-ene cyclization enabled access to 1-azaspiro[4.4]nonane and its application in a modular synthesis toward (±)-cephalotaxine

Cited by 29 publications

References 51 publications

Generation and Trapping of Nitrosocarbonyl Intermediates

Generation and Trapping of Nitrosocarbonyl Intermediates

Crossing the Ring: A Journey of the Nitroso-ene Reaction

Modified Ti-MWW Zeolite as a Highly Efficient Catalyst for the Cyclopentene Epoxidation Reaction

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