Propargyl ureas can lead to a range of possibleheterocycliccompounds,mainlydependingon theemployedcatalyst.Silver salts are knownto promotetheN-5-exo-digcyclizationmode to imidazolidinonederivatives.Conversely, a versatileand stereoselectiveO-5-exo-digcyclizationof propargyl ureas to 2-aminooxazolinesby Ag(I) catalysisis here disclosed.Good to excellentyields and completestereoselectivityof the externaldoublebond have been achievedunder milderreactionconditions(50–60°C). A one-potprotocolstartingfrom the correspondingpropargylic aminesand isocyanateshas been developedas well.N,N’-Dipropargyl ureas underwenta uncommonO-5-exo-dig/N-5-endo-digdoublecyclizationsequence.Finally, insightsinto the tautomericequilibriumof 2-aminooxazolesand on their relativereactivityareprovided.
Unexpected Stereoselective Access to 2‐Aminooxazolines from Propargyl Ureas by Silver Salts under Mild Conditions
Mancuso, Raffaella;Gabriele, Bartolo;
2023-01-01
Abstract
Propargyl ureas can lead to a range of possibleheterocycliccompounds,mainlydependingon theemployedcatalyst.Silver salts are knownto promotetheN-5-exo-digcyclizationmode to imidazolidinonederivatives.Conversely, a versatileand stereoselectiveO-5-exo-digcyclizationof propargyl ureas to 2-aminooxazolinesby Ag(I) catalysisis here disclosed.Good to excellentyields and completestereoselectivityof the externaldoublebond have been achievedunder milderreactionconditions(50–60°C). A one-potprotocolstartingfrom the correspondingpropargylic aminesand isocyanateshas been developedas well.N,N’-Dipropargyl ureas underwenta uncommonO-5-exo-dig/N-5-endo-digdoublecyclizationsequence.Finally, insightsinto the tautomericequilibriumof 2-aminooxazolesand on their relativereactivityareprovided.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
