| 摘要 |
A process for the production of 2H-1-benzopyrans with general formula (I) where R<1> is hydrogen, a (C1-C4) alkyl group, R<2> is hydrogen, a (C1-C6) alkyl group and R<3> is hydrogen, a (C1-C4) alkyl group, a (C1-C4) haloalkyl group, a (C2-C4) alkenyl group, a (C1-C4) alkoxycarbonyl group, a (C1-C4) alkoxymethyl group, a (C1-C4) alkanoyl group, a (C1-C4) alkoxy group, a (C1-C4) alkylsulphonyl group, halogen, amino, alkylamino, dialkylamino, nitril, nitro or hydroxy, is characterised in that in a first stage an aliphatic aldehyde with general formula (II) where R<1> and R<2> have the above-mentioned meaning, is converted with an aliphatic alcohol with the formula R<4>OH or HOR<4>OH, where R<4> is a (C1-C4) alkyl group or a (C2-C4) alkyldiyl group, in the presence of a dehydrating compound with the formula HC(OR<5>)3, where R<5> is a (C1-C4) alkyl group, and an aluminium oxide/silicium oxide catalyst into an aliphatic acetal with general formula (III) where R<1> and R<2> have the above-mentioned meaning and R<4> as stated above is a (C1-C4) alkyl group or the two R<4> together are a cyclical (C2-C4) alkyldiyl group, and this is then condensed in a second stage with a phenol with general formula (IV) where R<3> has the above-mentioned meaning, in the presence of a base in an inert organic solvent, to the end product with general formula (I).
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