Acyl Azides and Nitrenes

Lwowski, Walter

doi:10.1016/b978-0-12-633480-7.50008-0

Cited by 97 publications

(102 citation statements)

References 150 publications

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“…That system could result solely by a deep dehydration of original starch. In a consequence, such BG could be considered as a poor source of potential harmful · OH radicals and a free radical trap acting by addition to the double bond particularly efficient in case of singlet free radical species [29][30][31] .…”

Section: Polymer Chemistrymentioning

confidence: 99%

Radioprotective thermally generated free-radical dextrins

Tomasik¹,

Michalski²,

Bidzińska

et al. 2008

Sci. Bull.

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Section: Polymer Chemistrymentioning

confidence: 99%

Radioprotective thermally generated free-radical dextrins

Tomasik¹,

Michalski²,

Bidzińska

et al. 2008

Sci. Bull.

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“…[2] There is general consensus that the thermal Curtius rearrangement is a concerted reaction of the azides, not involving acylnitrenes (2). It is usually believed that the photochemical rearrangement can take two distinct paths: (i) Concerted Curtius rearrangement to isocyanate, and (ii) nitrene formation, which may or may not lead to isocyanate.…”

Section: Introductionmentioning

confidence: 99%

The Curtius Rearrangement of Acyl Azides Revisited – Formation of Cyanate (R–O–CN)

Wentrup

Bornemann

2005

Eur J Org Chem

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“…The most direct access to aziridines consists of nitrene addition to olefins [2] (Scheme I ) . Systems for aziridination of olefins in the presence of chiral transition-metal catalysts have been reported from several laboratories [3-51.…”

Section: Reactions Of Diazo Compounds With Iminesmentioning

confidence: 99%

Reactions of Diazo Compounds with Imines. Preliminary communication

Moran

Bérnardinelli

Müller

1995

Helvetica Chimica Acta

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(12.VI.95)The [Rh2(0Ac)4]-catalyzed addition of methyl diazoacetate to N-benzylideneaniline (la) afforded the imine cis-2 in 35% yield. Under catalysis by chiral Rh" catalysts, however, only racemic la was produced, and the yield was low. In the presence of dimethyl maleate, aziridine formation was suppressed, and an intermediate ylide 6 was trapped as cycloadduct 7. No aziridines were obtained, however, from lb, lc, and 3. The iminium salt 8 reacted with (trimethylsily1)diazomethane in the absence of [Rh,(OAc),] via dipolar cycloaddition followed by extrusion of Nz to 10.Aziridines are attractive intermediates in organic synthesis, and a variety of approaches to their synthesis have been investigated [ 11. The most direct access to aziridines consists of nitrene addition to olefins [2] (Scheme I ) . Systems for aziridination of olefins in the presence of chiral transition-metal catalysts have been reported from several laboratories [3-51. The decomposition of PhI=NTs by transition metals, first described by Mansuy and coworkers [3], has been successfully developed into a system for asymmetric aziridination by the groups of Evans et al. [6] and Jucobsen and coworkers [7] using chiral Cu catalysts. Aziridines are formed in high yield and with high enantiomeric excess. An alternative approach for catalytic generation of aziridines, consisting of carbene addition to imines, has been investigated in the past with limited success [%lo], and the general idea was that this was not a viable route to aziridines. R R )IVery recently, however, the Jucohsen group reported on the reactions between imines and ethyl diazoacetates in the presence of chiral Cu'-bis(dihydrooxazo1e) complexes [ 1 11. Aziridines were produced in moderate yields (10-370/0; 65 04 with an achiral bis(dihydr0-oxazole)) with ee's reaching 67 %. A mechanism involving an intermediate achiral ylide, weakly associated with the catalyst, was proposed to explain the low enantioselectivity of the carbene transfer. Asymmetric Rh-based cyclopropanation systems were also tried, but were found less satisfactory than those containing Cu. Subsequently, Ramussen and

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Acyl Azides and Nitrenes

Cited by 97 publications

References 150 publications

Radioprotective thermally generated free-radical dextrins

Radioprotective thermally generated free-radical dextrins

The Curtius Rearrangement of Acyl Azides Revisited – Formation of Cyanate (R–O–CN)

Reactions of Diazo Compounds with Imines. Preliminary communication

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