Radical-mediated carboxylation of alkyl iodides with [11C]carbon monoxide in solvent mixtures.
J Org Chem
; 70(6): 2244-9, 2005 Mar 18.
Article
em En
| MEDLINE
| ID: mdl-15760211
ABSTRACT
[reaction see text] [carboxyl-(11)C]Carboxylic acids were prepared from alkyl iodides via photoinitiated radical reactions using 10(-)(8) mol of [(11)C]carbon monoxide in binary and ternary homogeneous solvent mixtures. Short- (isobutyric), medium-, and long-chain saturated fatty acids (heptadecanoic) were labeled with isolated decay-corrected radiochemical yields ranging from 55% to 70% in 5-7-min reactions. The conversion of [(11)C]carbon monoxide to products reached 80-90%. To obtain good yields in the reactions performed in water-acetonitrile and water-THF mixtures, the addition of tetrabutylammonium hydroxide or potassium hydroxide was essential. The carboxylation was efficient for primary and secondary alkyl iodides. The carboxylation of tertiary iodides was feasible for 1-iodoadamantane but not for tert-butyl iodide. The dependence of the radiochemical yields on reaction time, photoirradiation conditions, and organic and inorganic additives was studied. The method provides a one-step route to [carboxyl-(11)C]carboxylic acids; traditional methods, in contrast, would require several steps. For example, using the devised reaction conditions, 3.19 GBq of purified [1-(11)C]1,10-decanedicarboxylic acid (specific radioactivity 188 GBq/mumol) was obtained within 35 min of the end of 10 muAh bombardment. (1-(13)C)4-Phenylbutyric acid was synthesized using ((13)C)carbon monoxide for identifying the labeling position with (1)H and (13)C NMR.
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01-internacional
Base de dados:
MEDLINE
Assunto principal:
Solventes
/
Monóxido de Carbono
/
Radicais Livres
/
Hidrocarbonetos Iodados
Idioma:
En
Revista:
J Org Chem
Ano de publicação:
2005
Tipo de documento:
Article
País de afiliação:
Suécia