Synthesis of Iodinated Naphthoquinones Using Morpholine‐Iodine Complex

Abstract

The efficient synthesis of 2‐hydroxy‐3‐iodo‐1,4‐naphthoquinone (3), 2‐amino‐3‐iodo‐1,4‐naphthoquinone (4), and 2‐iodo‐1,4‐naphthoquinone (5) have been developed using the parent naphthoquinone in combination with the charge‐transfer complex between iodine and morpholine.

Keywords:

• Iodination
• Lawsone
• Morpholine‐iodine complex
• Naphthoquinones

Acknowledgments

We are grateful to the Vicerrectoría de Investigación (UCR Project 809‐98‐231) for financial support and to Ms. L. Hernández (CIPRONA) for her technical assistance.

Notes

^aWe have found that naphthoquinones cannot be halogenated in high yields under oxidative conditions (decomposition) nor in the presence of metal ions (formation of chelates). The iodination does not go to completion using only elemental iodine (even in large excess).