En este articulo se presenta la oxidacion alilica del acido ent-kaurenico, del ester metilico del acido ent-kaurenico y del ent-kaurenol. La reaccion se realizo utilizando dioxano como solvente, a temperatura ambiente bajo agitacion durante 4 horas. Se trato aproximadamente 0,3 mmol de sustrato con 1,2 mmol de SeO2 y 4,1 mmol de H2O2. La oxidacion del acido ent-kaurenico produjo un 56% de acido ent-15�¿.hidroxi-kaur-16-en-19-oico (2a). La oxidacion del ester metilico del acido ent-kaurenico dio dos productos: el ester metilico del acido ent-15�¿.hidroxi-kaur-16-en-19-oico (2b, 34%) y el ester metilico del acido ent-15�¿-16�¿-epoxi-17-hidroxi-kauran-19-oico (3a, 59%). De manera similar la oxidacion del ent-kaurenol condujo a la formacion de dos productos: ent-15�¿,19-dihidroxi-kaur-16-eno (2c, 56,7%) y ent-15�¿-16�¿-epoxi-17,19 -dihidroxi-kaurano (3b, 34%). Experimentos realizados usando el doble o la mitad de H2O2 manteniendo constante la concentracion de SeO2, no produjeron cambios significativos en la proporcion y rendimiento de los productos de oxidacion.
The allylic oxidation of ent-kaurenic acid, ent-kaurenic acid methyl ester, and ent-kaurenol with SeO2/H2O2 is presented. The reaction was run in dioxan solution at room temperature stirring for 4 hours. About 0.3 mmol of substrate was treated with 1.2 mmol of SeO2 and 4.1 mmol of H2O2. Treatment of ent-kaurenic acid afforded 56% of ent-15á-hydroxy-kaur-16-en-19-oic acid (2a). Treatment of ent-kaurenic acid methyl ester afforded two products: ent-15á-hydroxy-kaur-16-en-19-oic acid methyl ester (2b, 34% yield) and ent-15á,16á-epoxi-17-hydroxy-kauran-19-oic acid methyl ester (3a, 59% yield). In a similar fashion treatment of ent-kaurenol rendered two products: ent-15á,17-dihydroxy-kaur-16-ene (2c, 56.7% yield) and ent-15á,16á-epoxi-17,19-dihydroxy-kaurane (3b, 34% yield). Additional experiments using twice as much or half as much H2O2 relative to the amount of SeO2 did not modify significantly the product ratio neither the yield.
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