The first example of a transoid amide (imide) in an eight-membered lactam
作者:P. Andrew Evans、Andrew B. Holmes、Ian Collins、Paul R. Raithby、Keith Russell
DOI:10.1039/c39950002325
日期:——
The Claisen rearrangement of the ketene aminal derived by selenoxide elimination of the seleno-aminal 1 in refluxing toluene in the presence of dihydropyran yields the expected unsaturated eight-membered lactam derivative 3, as well as two unexpected products 7a and 7b; the major product 7a(resulting from a selenium re-addition reaction) was shown by X-ray crystallography to be a highly distorted transoid amide (imide) with the largest p-orbital distortion (τ= 50.6°) recorded for a cyclic amide.
ketene aminals 4a-c which were generated in situ by selenoxide elimination of the aminal precursors 3a-c in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene gave the monocyclic unsaturated mediumringlactams 5a-c.
New methodology for the synthesis of unsaturated 8-, 9- and 10-membered lactams
作者:P. Andrew Evans、Andrew B. Holmes、Ross P. McGeary、Alan Nadin、Keith Russell、Peter J. O'Hanlon、Neil D. Pearson
DOI:10.1039/p19960000123
日期:——
Unsaturated 8-, 9- and 10-membered medium ring lactams 1 (n= 1,2,3) have been prepared in good yield by the Claisen rearrangement of the vinyl-substituted precursors 3 in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU).