A variety of 3-functionalized benzo[b]furans were achieved by way of a FeCl(3)-mediated intramolecular cyclization of electron-rich alpha-aryl ketones. The alkoxy substituent on the benzene ring in the substrates was essential for an efficient cyclization to occur. This novel method allows the construction of benzo[b]furan rings by joining the O-atom on the side chain to the benzene ring via direct oxidative aromatic C-O bond formation.
The conjugate addition of hydroxylamines, oximes and hydroxamic acids provides convenient route to incorporate an NO moiety into various Michael acceptors. This chapter reviews comprehensive experimental reactions on the formation of carbon–nitrogen and carbon–oxygen bonds via conjugate addition of hydroxylamines, oximes and hydroxamic acids to alkenes, alkynes or allenes attached to one or more electron‐withdrawing groups. Hydroxylamine derivatives predominantly undergo N‐centered conjugate addition, while for the ambient nucleophilic oximes and hydroxamic acids, both N‐centered and O‐centered conjugate addition are operative by control of the reaction conditions. A concerted cycloaddition mechanism has been well established for the conjugate addition of
N
‐substituted hydroxylamines. The last decade has witnessed enormous growth in enantioselective conjugate addition of hydroxylamine derivatives and the O‐centered oximes.
General Introduction
Conjugate Addition of Hydroxylamine and Itsderivatives
Conjugate Addition of Oximes
Conjugate Addition of Hydroxamic Acids
Conclusions
Acknowledgments
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