ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Boron Trifluoride Catalyzed Reaction of 3-Amino-2H-azirines and Amides: Formation of 4,4-Disubstituted 4H-ImidazolesReaction of trifluoroacetamide and 3-amino-2H-azirines 1 in refluxing MeCN affords 4-amino-2-(trifluoromethyl)-4H-imidazoles 5 in fair yields (Scheme 3). Less acidic amides do not react with 1 under similar conditions. Therefore, a procedure involving BF3-catalysis has been elaborated: the aminoazirine 1 in CH2Cl2 at -78° is treated with BF3 · Et2O and then with a solution of the sodium salt of an amide in THF, prepared by addition of sodium hexamethyldisilazane at -78°. The 4H-imidazoles of type 5 are formed in ca. 50% yield (Scheme 4). Reaction mechanisms for this ring enlargement of 1 are proposed in Schemes 5 and 6.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19950780413