Radioiodination of 7‐methoxy‐ and 6,7‐dimethoxy‐4‐bromomethylcoumarins

Janina Baranowska‐Kortylewicz, Zbigniew P. Kortylewicz

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Two coumarins, 4‐bromomethyl‐6,7‐dimethoxy‐2‐oxo‐2H‐benzopyran (1) and 4‐bromomethyl‐7‐methoxy‐2‐oxo‐2H‐benzopyran (3), were radioiodinated using trifluoroacetyl hypoiodite. The dimethoxy derivative 1 gave only a single regioisomer 3‐[125I]iodo‐4‐bromo‐methyl‐6,7‐dimethoxy‐2‐oxo‐2H‐benzopyran (2). The average yield for no‐carrier‐added preparations of 2 was 30%. 125/127I‐2 and 127I‐2 were produced in over 50% yield. In no‐carrier‐added syntheses 7‐methoxy‐coumarin 3 gave 3‐[125I]iodo‐4‐bromomethyl‐7‐methoxy‐2‐oxo‐2H‐benzopyran(5) as the major product (30%) accompanied by a small amount (3–7%) of the 6‐[125I]iodo‐analog 4. When an equimolar amount of iodide was used (i.e. carrier‐added syntheses) 4 and 5 were produced in over 20% yield each. Under these conditions the 8‐iodo‐regioisomer was not formed from either 1 or 3 possibly as the result of steric effects. Sonication greatly accelerated rates of radioiodination reducing the time required to achieve quantitative substitution of 127I from about 4 h to 20 min.

Original languageEnglish (US)
Pages (from-to)1301-1307
Number of pages7
JournalJournal of Labelled Compounds and Radiopharmaceuticals
Volume29
Issue number12
DOIs
StatePublished - Dec 1991

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Coumarins
Sonication
Iodides
Substitution reactions
Derivatives
hypoiodous acid

Keywords

  • 4‐bromomethyl‐6,7‐dimethoxy‐2‐oxo‐2H‐benzopyran
  • 4‐bromomethyl‐7‐methoxy‐2‐oxo‐2H‐benzopyran
  • I‐radioiodination
  • coumarin
  • trifluoroacetyl hypoiodite

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Radiology Nuclear Medicine and imaging
  • Drug Discovery
  • Spectroscopy
  • Organic Chemistry

Cite this

Radioiodination of 7‐methoxy‐ and 6,7‐dimethoxy‐4‐bromomethylcoumarins. / Baranowska‐Kortylewicz, Janina; Kortylewicz, Zbigniew P.

In: Journal of Labelled Compounds and Radiopharmaceuticals, Vol. 29, No. 12, 12.1991, p. 1301-1307.

Research output: Contribution to journalArticle

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N2 - Two coumarins, 4‐bromomethyl‐6,7‐dimethoxy‐2‐oxo‐2H‐benzopyran (1) and 4‐bromomethyl‐7‐methoxy‐2‐oxo‐2H‐benzopyran (3), were radioiodinated using trifluoroacetyl hypoiodite. The dimethoxy derivative 1 gave only a single regioisomer 3‐[125I]iodo‐4‐bromo‐methyl‐6,7‐dimethoxy‐2‐oxo‐2H‐benzopyran (2). The average yield for no‐carrier‐added preparations of 2 was 30%. 125/127I‐2 and 127I‐2 were produced in over 50% yield. In no‐carrier‐added syntheses 7‐methoxy‐coumarin 3 gave 3‐[125I]iodo‐4‐bromomethyl‐7‐methoxy‐2‐oxo‐2H‐benzopyran(5) as the major product (30%) accompanied by a small amount (3–7%) of the 6‐[125I]iodo‐analog 4. When an equimolar amount of iodide was used (i.e. carrier‐added syntheses) 4 and 5 were produced in over 20% yield each. Under these conditions the 8‐iodo‐regioisomer was not formed from either 1 or 3 possibly as the result of steric effects. Sonication greatly accelerated rates of radioiodination reducing the time required to achieve quantitative substitution of 127I from about 4 h to 20 min.

AB - Two coumarins, 4‐bromomethyl‐6,7‐dimethoxy‐2‐oxo‐2H‐benzopyran (1) and 4‐bromomethyl‐7‐methoxy‐2‐oxo‐2H‐benzopyran (3), were radioiodinated using trifluoroacetyl hypoiodite. The dimethoxy derivative 1 gave only a single regioisomer 3‐[125I]iodo‐4‐bromo‐methyl‐6,7‐dimethoxy‐2‐oxo‐2H‐benzopyran (2). The average yield for no‐carrier‐added preparations of 2 was 30%. 125/127I‐2 and 127I‐2 were produced in over 50% yield. In no‐carrier‐added syntheses 7‐methoxy‐coumarin 3 gave 3‐[125I]iodo‐4‐bromomethyl‐7‐methoxy‐2‐oxo‐2H‐benzopyran(5) as the major product (30%) accompanied by a small amount (3–7%) of the 6‐[125I]iodo‐analog 4. When an equimolar amount of iodide was used (i.e. carrier‐added syntheses) 4 and 5 were produced in over 20% yield each. Under these conditions the 8‐iodo‐regioisomer was not formed from either 1 or 3 possibly as the result of steric effects. Sonication greatly accelerated rates of radioiodination reducing the time required to achieve quantitative substitution of 127I from about 4 h to 20 min.

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