Communication
Green Chemistry
(entry 11). In addition, with regard to the oxidants, this
reaction requires only 26.7 mg of 7 and 18.9 mg of FePc.
Acknowledgements
In comparison, anaerobic stoichiometric oxidation would This work was generously supported by the Swedish Research
need at least 2.48 g of quinone 1 to achieve a similar result. Council VR and FORMAS, Magnus Bergvalls stiftelse and
The oxidative esterifications run very clean, none of the Chalmers Areas of Advance Nano.
expected byproducts can be detected in crude NMR, which
simplifies purification. It also signifies the very high selectivity
in each catalytic step of this multi-component reaction. More-
over, the method provides a mild direct access to unsaturated
Notes and references
esters from aldehydes, which circumvents oxidation to the
carboxylic acid that traditionally is the starting point in ester
formation. Recycling experiments showed that addition of
new starting materials to the reaction vessel was successful
and compound 3 could be obtained in average 71% yield
over three cycles (see the ESI†). These results confirm that the
catalytic system is not degraded over the course of the reaction
and that it would be possible to design a system for recover
and reuse.
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aldehyde (Scheme 3).5a,c,29 The approach proved viable and
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Scheme 3 Syntheses of lactones 24–26. See the ESI† for experimental
details. Yields refer to the isolated product.
Green Chem.
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