Synthesis of Imidazolidin-2-ones and Imidazol-2-ones via Base-Catalyzed Intramolecular Hydroamidation of Propargylic Ureas under Ambient Conditions.
J Org Chem
; 84(6): 3477-3490, 2019 03 15.
Article
in En
| MEDLINE
| ID: mdl-30788963
ABSTRACT
The first organo-catalyzed synthesis of imidazolidin-2-ones and imidazol-2-ones via intramolecular hydroamidation of propargylic ureas is reported. The phosphazene base BEMP turned out to be the most active organo-catalyst compared with guanidine and amidine bases. Excellent chemo- and regioselectivities to five-membered cyclic ureas have been achieved under ambient conditions, with a wide substrate scope and exceptionally short reaction times (down to 1 min). A base-mediated isomerization step to an allenamide intermediate is the most feasible reaction pathway to give imidazol-2-ones, as suggested by DFT studies.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
J Org Chem
Year:
2019
Document type:
Article
Affiliation country:
Italy