Aza- 3,3 -claisen enolate rearrangement in vinylaziridines : Stereoselective synthesis of mono-, di-, and trisubstituted seven-membered lactams

• Several 2,3-disubstituted vinylaziridines have been N-acylated and subjected to LiHMDS in THF at - 78 degreesC. Upon warming to room temperature, the resulting amide enolates underwent a highly stereoselective [3,3]-sigmatropic rearrangement to give mono-, di-, and trisubstituted seven-membered lactams in good yields. The scope and limitations of the process have been investigated by using variously substituted vinylaziridines. A kinetically controlled process proceeding through a six-membered boatlike transition state assembly has been invoked to explain the stereochemical outcome of the reaction.

Nyckelord

C-C coupling

lactams

rearrangements

vinylaziridines

aza-wittig rearrangement

aza-<2,3>-wittig rearrangements

pyrrolizidine alkaloids

organocopper reagents

claisen rearrangement

entry

selectivity

annulation

aminolysis

isosteres

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