Propargyl ureas can lead to a range of possible heterocyclic compounds, mainly depending on the employed catalyst. Silver salts are known to promote the N-5-exo-dig cyclization mode to imidazolidinone derivatives. Conversely, a versatile and stereoselective O-5-exo-dig cyclization of propargyl ureas to 2-aminooxazolines by Ag(I) catalysis is here disclosed. Good to excellent yields and complete stereoselectivity of the external double bond have been achieved under milder reaction conditions(50–60°C). A one-po protocol starting from the corresponding propargylic amines and isocyanates has been developed as well. N,N’-Dipropargyl ureas underwent a uncommon O-5-exo-dig/N-5-endo-dig double cyclization sequence. Finally, insights into the tautomeric equilibrium of 2-aminooxazoles and on their relative reactivity are provided.

Unexpected Stereoselective Access to 2-Aminooxazolines from Propargyl Ureas by Silver Salts under Mild Conditions / Voronov, A.; Casnati, A.; Mazzeo, P. P.; Pelagatti, P.; Bacchi, A.; Mancuso, R.; Gabriele, B.; Motti, E.; Maestri, G.; Feher, P. P.; Stirling, A.; Della Ca', N.. - In: ADVANCED SYNTHESIS & CATALYSIS. - ISSN 1615-4150. - (2022), pp. 1-9. [10.1002/adsc.202200950]

Unexpected Stereoselective Access to 2-Aminooxazolines from Propargyl Ureas by Silver Salts under Mild Conditions

Voronov A.;Casnati A.;Mazzeo P. P.;Pelagatti P.;Bacchi A.;Motti E.;Maestri G.;Della Ca' N.
2022-01-01

Abstract

Propargyl ureas can lead to a range of possible heterocyclic compounds, mainly depending on the employed catalyst. Silver salts are known to promote the N-5-exo-dig cyclization mode to imidazolidinone derivatives. Conversely, a versatile and stereoselective O-5-exo-dig cyclization of propargyl ureas to 2-aminooxazolines by Ag(I) catalysis is here disclosed. Good to excellent yields and complete stereoselectivity of the external double bond have been achieved under milder reaction conditions(50–60°C). A one-po protocol starting from the corresponding propargylic amines and isocyanates has been developed as well. N,N’-Dipropargyl ureas underwent a uncommon O-5-exo-dig/N-5-endo-dig double cyclization sequence. Finally, insights into the tautomeric equilibrium of 2-aminooxazoles and on their relative reactivity are provided.
Unexpected Stereoselective Access to 2-Aminooxazolines from Propargyl Ureas by Silver Salts under Mild Conditions / Voronov, A.; Casnati, A.; Mazzeo, P. P.; Pelagatti, P.; Bacchi, A.; Mancuso, R.; Gabriele, B.; Motti, E.; Maestri, G.; Feher, P. P.; Stirling, A.; Della Ca', N.. - In: ADVANCED SYNTHESIS & CATALYSIS. - ISSN 1615-4150. - (2022), pp. 1-9. [10.1002/adsc.202200950]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11381/2933691
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