Solution and flash vacuum pyrolysis of some 2,6-disubstituted .beta.-phenethylsulfonyl azides and of .beta.-styrenesulfonyl azide

Abramovitch, R. A.; Kress, Albert O.; Pillay, K. S.; THOMPSON, W. M.

doi:10.1021/jo00212a013

Cited by 9 publications

(3 citation statements)

References 2 publications

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“…FVP of the dichloro derivative 374 at 400 °C (0.5 hPa, N 2 flow) afforded the sultam 375 , where one chlorine has been lost, in 34% yield, whereas thermolysis in Freon-113 at 185 °C resulted in compound 376 , in which a chlorine shift has taken place (eq ). The formation of pyridine derivatives in some of these reactions suggests that the sulfonylnitrenes may also add to the benzene rings with formation of azepine intermediates. …”

Section: Azidesmentioning

confidence: 99%

Flash Vacuum Pyrolysis of Azides, Triazoles, and Tetrazoles

2017

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Flash vacuum pyrolysis (FVP) of azides is an extremely valuable method of generating nitrenes and studying their thermal rearrangements. The nitrenes can in many cases be isolated in low-temperature matrices and observed spectroscopically. NH and methyl, alkyl, aralkyl, vinyl, cyano, aryl and N-heteroaryl, acyl, carbamoyl, alkoxycarbonyl, imidoyl, boryl, silyl, phosphonyl, and sulfonyl nitrenes are included. FVP of triazoloazines generates diazomethylazines and azinylcarbenes, which often rearrange to the energetically more stable arylnitrenes. N elimination from monocyclic 1,2,3-triazoles can generate iminocarbenes, 1H-azirines, ketenimines, and cyclization products, and 1,2,4-triazoles are precursors of nitrile ylides. Benzotriazoles are preparatively useful precursors of cyanocyclopentadienes, carbazoles, and aza-analogues. FVP of 5-aryltetrazoles can result in double N elimination with formation of arylcarbenes or of heteroarylcarbenes, which again rearrange to arylnitrenes. Many 5-substituted and 2,5-disubstituted tetrazoles are excellent precursors of nitrile imines (propargylic, allenic, or carbenic), which are isolable at low temperatures in some cases (e.g., aryl- and silylnitrile imines) or rearrange to carbodiimides. 1,5-Disubstituted tetrazoles are precursors of imidoylnitrenes, which also rearrange to carbodiimides or add intramolecularly to aryl substituents to yield indazoles and related compounds. Where relevant for the mechanistic understanding, pyrolysis under flow conditions or in solution or the solid state will be mentioned. Results of photolysis reactions and computational chemistry complementing the FVP results will also be mentioned in several places.

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Section: Azidesmentioning

confidence: 99%

Flash Vacuum Pyrolysis of Azides, Triazoles, and Tetrazoles

2017

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“…Introduction of a propenyl group by cross-metathesis using Grubbs’ second-generation catalyst and 2-methyl-2-butene was followed by formation of the indole ring by treatment with P(OEt) 3 at 170 °C (Scheme ) . Hydrolysis of compound 13 , followed by decarboxylation using copper powder in quinoline, gave the protected aurantioclavine 14 . Finally, removal of the Ts group using sodium naphthalenide completed the total synthesis of (−)-aurantioclavine ( 1 ).…”

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confidence: 99%

Asymmetric Synthesis of (−)-Aurantioclavine via Palladium-Catalyzed Intramolecular Allylic Amination

et al. 2014

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The total synthesis of (-)-aurantioclavine (1) was accomplished based on an intramolecular asymmetric amination of allyl carbonate 3 containing a p-tosylamide group. The reaction using tris(dibenzylideneacetone)dipalladium(0), tBu-phosphinooxazoline, and Bu4NCl in CH2Cl2 gave azepane 2 in 77% yield with 95% enantiomeric excess. The obtained azepane 2 was also converted to a substructure of communesin F.

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“…The resultant benzylic bromide 14 was immediately converted to the corresponding benzylic cyanide 15 . Finally, the cyano group was methanolyzed to ester 16 followed by Sonogashira coupling to ortho ester 8 with subsequent ortho ester hydrolysis to afford the fully elaborated cyclization substrate 17 . It should be noted that attempts to carry out the Sonogashira coupling with the bromide gave poor results, thus requiring the change from bromide 12 to iodide 13 .…”

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confidence: 99%