Oxofunctionalized Trans-2-carboxycinnamic Acids by Catalytic Domino Oxidation of Naphthols and Hydronaphthoquinones

Abstract

The catalytic oxidation of naphthalenes was investigated. Hydrogen peroxide (30% aqueous) was used as an oxygen source, and 2,2’-dinitro-4,4’-ditrifluoromethyldiphenyl diselenide was the oxygen-transfer catalyst. Unsubstituted naphthols produce trans-2-carboxycinnamic acid in nearly quantitative yields. Both naphthols bearing substituents on the conjugated ring deliver corresponding trans-2-carboxycinnamic acids in good to excellent yields. The 1,7- and 2,6-hydronaphthoquinones, substituted by carboxy and carboxymethyl groups, produce hydroxycinnamic acids in satisfactory to excellent yields. A catalytic domino reaction mechanism is proposed.

GRAPHICAL ABSTRACT

Keywords:

• Catalysis
• cinnamic acids
• domino reaction
• naphthalenes
• oxidation
• selenium

ACKNOWLEDGMENTS

We are grateful to Jacek Młochowski and Ludwik Syper for valuable discussions. This work was supported by the Polish State Committee for Scientific Research (Grant No. S10132/20305).

Notes

^a Preparative yield. Data in parantheses refer to the yield determined by ¹H NMR.

^b Ref. [17]: mp 204–205 °C; ref. [46]: mp 170.5–205 °C.

^c Unreacted substrate 1a was isolated in 70–95% yield.

^d Yellow solid was formed.

^a Preparative yield. Data in parantheses refer to the yield determined by ¹H NMR.

^b Mixture of polymeric 2,6-naphthoquinone was formed.

^c 1.5 eq. of H₂O₂ was used.