142065-23-4Relevant articles and documents
Semiconductor-Catalysed Photoaddition of Olefins and Enol Ethers to 1,2-Diazenes: A New Route to Allylhydrazines
Kuenneth, Ronald,Feldmer, Christian,Knoch, Falk,Kisch, Horst
, p. 441 - 448 (2007/10/03)
Suspensions of zinc or cadmium sulfide powders in a protic solvent catalyse the linear addition of enol ethers and olefins to 1,2-diaryl- and 1-aryl-2-alkyl-1,2-diazenes, producing allylhydrazine derivatives.Relative quantum yields decrease sharply when the 1,2-diazene is more difficult to reduce, while their relationship to the oxidation potential of the enol ether/olefin is complicated.Reduction to 1,2-diarylhydrazine and concomitant dehydrodimerization of the enol ether occurs as a side reaction.It is favoured by increasing light intensity and becomes the major reaction path when platinized (5 molpercent) photocatalysts are employed.It is proposed that the photogenerated electron-hole pair in a proton-coupled electron transfer reduces the diazene to a hydrazyl radical and oxidizes the olefin/enol ether to a radical cation.The allylic radical obtained from the latter by deprotonation then undergoes C-N coupling with the hydrazyl radical to afford the allylhydrazine.Diarylhydrazine formation occurs by disproportionation of the hydrazyl radical or by a successive proton-coupled reduction.Thus photoaddition can be classified as a 1e(-)/1h(+) process while 2e(-)/2h(+) are necessary for the reduction. - Keywords: allylhydrazines, cadmium compounds, catalysis, photochemistry, zinc compounds
