Details

Autor(en) / Beteiligte

• He, Ming

Titel

Enantioselective, N-heterocyclic carbene catalyzed annulations

Erscheinungsjahr

2007

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The development of N-heterocyclic carbene (NHC)-catalyzed annulations via the catalytic generation of reaction intermediates has been described. We have developed the direct annulations of enals and N-sulfonylimines to synthesize gamma-lactams via homoenolates addition to imines. The key to the success is the choice of the protecting group on the imine to overcome nucleophilic inhibition. Having achieved the protonation of homoenolates to afford enolates, we have discovered enantioselective, NHC-promoted, inverse electron demand Diels-Alder reactions. We have extended the enolate precursors from enals to alpha-chloroaldehydes and to the corresponding sodium bisulfite adducts. We have also shown that both azadienes and oxodienes are reactive substrates in the Diels-Alder cycloadditions. In these processes, low catalyst loadings have been achieved. Finally, we have developed enantioselective, NHC-catalyzed bicyclo-beta-lactam formation via direct annulations of enals and unsaturated N-sulfonyl ketimines, which feature an benzoin-oxy-Cope cascade reaction.