Synthesis of Spiranes by Thiol‐Mediated Acyl Radical Cyclization

Hsu, Day‐Shin; Chen, Chih‐Hao; Hsu, Chi-Wei

doi:10.1002/ejoc.201501305

Cited by 28 publications

(15 citation statements)

References 31 publications

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“…been reported previously on the basis of avariety of strategies for the construction of the azaspirobicyclic system. However, no strategy based on radical cyclization [6,7] has been reported so far for the stereocontrolled construction of the spirocyclic system in an optically active form. Herein we report the total synthesis of (À)-HTX (1)and (À)-HTX 235A (2)through the stereoselective construction of the 1-azaspiro [5.5]undecane core by ad iastereoselective radical translocation-cyclization cascade.…”

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confidence: 99%

Total Synthesis of (−)‐Histrionicotoxin through a Stereoselective Radical Translocation–Cyclization Reaction

et al. 2016

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Stereoselective total syntheses of (-)-histrionicotoxin and (-)-histrionicotoxin 235A are described. The 1-azaspiro[5.5]undecane skeleton was constructed diastereoselectively by a radical translocation-cyclization reaction involving a chiral cyclic acetal; the use of tris(trimethylsilyl)silane was crucial for the high diastereoselectivity. The cyclization product was converted into (-)-histrionicotoxin 235A through a one-pot partial-reduction-allylation reaction of a derivative containing an unprotected lactam. Finally, two terminal alkenes were transformed into enynes with the 1,3-amino alcohol protected as an oxathiazolidine oxide to complete the total synthesis of (-)-histrionicotoxin.

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confidence: 99%

Total Synthesis of (−)‐Histrionicotoxin through a Stereoselective Radical Translocation–Cyclization Reaction

et al. 2016

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“…As the mechanism aforementioned, once the aminoalkyl radical yielded, it was transferred to acryloxy group and the propagation of radical occurred. The intramolecular free radical conjugated additions have been widely demonstrated as the useful tools in the construction of cyclic molecules . Thus, it implied the possibility of the formation of the cyclic molecules or intermediates in our case.…”

Section: Resultsmentioning

confidence: 81%

“…The intramolecular free radical conjugated additions have been widely demonstrated as the useful tools in the construction of cyclic molecules. [13][14][15][16] Thus, it implied the possibility of the formation of the cyclic molecules or intermediates in our case. For clarity, one of the proposed main existing species of TX-PA, TX-EA, and TX-BDA were presented to be A, B, and C in Figure 3, respectively.…”

Section: Visible Light Photolysismentioning

confidence: 95%

High‐Performance and Low Migration One‐Component Thioxanthone Visible Light Photoinitiators

Tang

Xiong

et al. 2017

Macro Chemistry & Physics

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Two thioxanthone based acrylated one‐component visible light photoinitiators, 2‐(methyl(4‐((methyl(9‐oxo‐9H‐thioxanthen‐2‐yl)amino)methyl)benzyl)amino)ethyl acrylate (TX‐EA) and ((4‐((methyl(9‐oxo‐9H‐thioxanthen‐2‐yl)amino)methyl)benzyl)azanediyl)bis(ethane‐2,1‐diyl)diacrylate (TX‐BDA), are designed and synthesized. The results of photopolymerization and migration study demonstrate that TX‐EA and TX‐BDA are more effective one‐component visible light photoinitiators for free radical polymerization with excellent migration stability than 4‐((methyl(9‐oxo‐9H‐thioxanthen‐2‐yl)amino)methyl)phenyl acrylate. The mass fraction of the extracted TX‐BDA in a cured 1,6‐hexanediol diacrylate polymer film is as low as 0.55% and the residual amount is estimated to be only 90 ppm. TX‐BDA would have great potential to be used in visible light curing systems, particularly in the food packing or biomedical fields. Results demonstrate that the synergistic effect of hydrogen donors and polymerizable groups in photoinitiator plays an important role in realizing high performance and low migration in photopolymerization system.

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“…[17] As elective allylation of 7 by aB arbier coupling reaction [18] in the presence of an enone group afforded the dienone 6 in 90 %yield. [17] As elective allylation of 7 by aB arbier coupling reaction [18] in the presence of an enone group afforded the dienone 6 in 90 %yield.…”

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confidence: 99%

Total Synthesis of Aplydactone by a Conformationally Controlled C−H Functionalization

et al. 2017

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A concise, protecting-group-free total synthesis of the unusual brominated sesquiterpene aplydactone is described. Our synthesis features a [2+2] photocycloaddition, a Wolff ring contraction, an unusual remote C-H functionalization to establish the highly strained tetracyclic core, and a hydrogen-atom transfer (HAT) reaction to access the bromine-containing stereocenter. A finely tuned conformation of the α-diazoketone precursor is the key for the success of the late-stage transannular C-H insertion to deliver a bridged six-membered ring and a quaternary stereocenter (C6) between two quaternary carbon atoms (C1 and C7).

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Synthesis of Spiranes by Thiol‐Mediated Acyl Radical Cyclization

Abstract: A general and efficient method for the preparation of spiro compounds is described. Various enone‐aldehydes were exposed to t‐dodecanethiol and AIBN at 75 °C in toluene to afford spirocyclic 1,4‐diketones in moderate to good yields.

Cited by 28 publications

References 31 publications

Total Synthesis of (−)‐Histrionicotoxin through a Stereoselective Radical Translocation–Cyclization Reaction

Total Synthesis of (−)‐Histrionicotoxin through a Stereoselective Radical Translocation–Cyclization Reaction

High‐Performance and Low Migration One‐Component Thioxanthone Visible Light Photoinitiators

Total Synthesis of Aplydactone by a Conformationally Controlled C−H Functionalization

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