Journal of Heterocyclic Chemistry
Volkan Kumbaraci, Duygu Ergunes, Melike Midilli, Seckin Begen, Naciye Talinli
The reaction of vinyl ethers with o-hydroxybenzyl alcohols under different reaction conditions was investigated. The aim of this attempt was to find out whether the protection reactions or the hetero DielsAlder reaction of quinone methidein situ generated from o-hydroxybenzyl alcohol is more likely to occur. o-hydroxybenzyl alcohols can give hetero DielsAlder reactions with dihydro-2H-pyran at high temperatures but only when used with acid catalysts. At room temperature, even in the presence of acid catalyst, reactions yielded regular protection products. However, butyl vinyl ether and 4-methoxy-3-butenone could not give intermolecularcycloaddition reactions under the acidic conditions, because both decomposed to the new products with acids. Hetero-DielsAlder products obtained only under thermal conditions but in low yields.