| 摘要 |
Preparation of 5-disubstituted 1,3-dioxan-4,6-diones un-, mono- or di-substituted in the 2-position comprises reacting 3C carboxylic acids un-, mono- or di-substituted in the 2-position with ketones using Lewis or protonic acids, whilst simultaneously crystallizing and/or distilling. Preparation of 5-disubstituted 1,3-dioxan-4,6-diones of formula (I) un-, mono- or di-substituted in the 2-position comprises reacting 3C carboxylic acids un-, mono- or di-substituted in the 2-position with ketones of formula R<3>COR<4> in monocarboxylic anhydrides or 2-4C monocarboxylic acids using Lewis or protonic acids, whilst simultaneously crystallizing and/or distilling: R<1> and R<2> = H or 1-6C (cyclo)aliphatic group or are coupled to a spiro; and R<3> and R<4> = 1-6C hydrocarbon or 6-2C aryl, alkylaryl or aralkyl.
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