Molecules 2013, 18(12), 15613-15623; doi:10.3390/molecules181215613
Article

Total Synthesis of Six 3,4-Unsubstituted Coumarins

Received: 28 October 2013; in revised form: 8 December 2013 / Accepted: 10 December 2013 / Published: 13 December 2013
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: In this article we describe a new methodology for the total synthesis of 3,4-unsubstituted coumarins from commercially available starting materials. Six examples were prepared, including five naturally occurring coumarins—7-hydroxy-6,8-dimethoxy-coumarin (isofraxidin), 7-hydroxy-6-methoxycoumarin (scopoletin), 6,7,8-trimethoxy-coumarin, 6,7-dimethoxycoumarin (scoparone), and 7,8-dihydroxycoumarin (daphnetin) and one synthetic coumarin, 7-hydroxy-6-ethoxycoumarin. Moreover, five important o-hydroxybenzaldehyde intermediates were also obtained, namely 2,4-dihydroxy-3,5-dimethoxybenzaldehyde, 2,4-dihydroxy-5-methoxybenzaldehyde, 5-ethoxy-2,4-dihydroxy-benzaldehyde, 2-hydroxy-3,4,5-trimethoxybenzaldehyde, and 2-hydroxy-4,5-dimethoxy-benzaldehyde. The method developed herein involves just three or four steps and allows for the rapid synthesis of these important molecules in excellent yields. This is the first synthesis of 6,7,8-trimethoxycoumarin and 7-hydroxy-6-ethoxycoumarin.
Keywords: 3,4-unsubstituted coumarins; o-hydroxybenzaldehyde derivatives; 6,7,8-trimethoxycoumarin; 7-hydroxy-6-ethoxycoumarin
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MDPI and ACS Style

Gao, W.; Li, Q.; Chen, J.; Wang, Z.; Hua, C. Total Synthesis of Six 3,4-Unsubstituted Coumarins. Molecules 2013, 18, 15613-15623.

AMA Style

Gao W, Li Q, Chen J, Wang Z, Hua C. Total Synthesis of Six 3,4-Unsubstituted Coumarins. Molecules. 2013; 18(12):15613-15623.

Chicago/Turabian Style

Gao, Wenqing; Li, Qingyong; Chen, Jian; Wang, Zhichao; Hua, Changlong. 2013. "Total Synthesis of Six 3,4-Unsubstituted Coumarins." Molecules 18, no. 12: 15613-15623.

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