70871-45-3Relevant articles and documents
Feigenbaum et al.
, p. 537 (1979)
Radical chain reactions of α-azido ketones with tributyltin hydride: Reduction vs nitrogen insertion and 1,2-hydrogen shift in the intermediate N-stannylaminyl radicals
Benati, Luisa,Leardini, Rino,Minozzi, Matteo,Nanni, Daniele,Spagnolo, Piero,Strazzari, Samantha,Zanardi, Giuseppe,Calestani, Gianluca
, p. 3485 - 3492 (2007/10/03)
The radical chain reactions of a variety of acyclic and cyclic α-azido ketones with tributyltin hydride have been investigated. The derived N-(tributylstannyl)aminyl radicals normally undergo H-abstraction reaction yielding corresponding amines, and thence symmetrical pyrazines by subsequent self-condensation, in competition with 1,2-H-migration from the α-carbon to nitrogen leading to α-imino ketone decomposition products with loss of the chain-carrying tributyltin radical. The noteworthy occurrence of a quite uncommon radical 1,2-hydrogen-atom shift is considered to be largely due to consequent formation of a highly stable, captodative carbon-centred radical. In contrast with our previous N-stannylaminyl radicals produced from α-azido-β-keto esters, the present aminyl congeners give poor amounts (or even none) of nitrogen-inserted amides/lactams, which are envisaged to arise from intramolecular three-membered cyclisation onto the ketone moiety followed by β-scission of the resultant alkoxyl radical. It is inferred that adequate stabilisation of the eventual ring-opened carbon radical be a major factor for the successful outcome of the regiospecific nitrogen insertion process. Evidence is also presented that chemoselective attack of tris(trimethylsilyl)silyl radical to the ketone oxygen of an α-azido ketone gives rise to deazidation as a likely consequence of β-elimination of azidyl radical by the ensuing α-silyloxyalkyl radical. X-Ray crystal structure analyses of the bromo ketone 5a, the azido ketone 5b, the caprolactam 22, and the pyrazine 26 have been performed.
Conjugate addition of lithium diorganocuprate reagents to the enol tosylate of a 1,2-diketone
Charonnat,Mitchell,Keogh
, p. 315 - 318 (2007/10/02)
The conjugate addition of lithium diorganocuprate reagents to the enol tosylate of 1,2-cyclohexanedione has been investigated. The intermediate enolates eliminate para-toluenesulfinate ion to generate the alkylated 1,2-dicarbonyl system.
