Piancatelli rearrangements, aza

An intramolecular aza-Piancatelli rearrangement that constructs a fully substituted carbon centre bearing a nitrogen atom and a spirocyclic ring system in a single operation has been catalysed by dysprosium (Ill)triflate. The azaspirocycles are formed exclusively as the irons diastereomer, consistent with a electrocyclization (Scheme 99). ... 

The aza-Piancatelli rearrangement of furans was used to form a functionalized cyclopentenone.This reaction allows the formation of congested vicinal stereogenic centers through a 4Jt-electrocyclization process (13OL3250). 

The aza-Piancatelli rearrangement of furylcarbinols and anilines can be triggered by Dy(OTf)3 to give 5-substituted-4-aminocyclopentenones with exclusive trans-selectivity (eq 6). This rearrangement is also proposed to terminate in a conrotatory 4it C-C bond-forming electrocyclization. 

In addition to the intermolecular aza-Piancatelli rearrangement, Dy(OTf)3 has been found to catalyze the intramolecular aza-Piancatelli rearrangement that provides access to nitrogen spiro-cycles (eq 7). ... 

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See also in sourсe #XX -- [ ]

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