Tetrahydro-pyrane-2,4-diones prepn. - by reacting acetoacetate dianiion with carbonyl cpds.

    公开(公告)号:DE2400429A1

    公开(公告)日:1975-07-17

    申请号:DE2400429

    申请日:1974-01-05

    Applicant: BASF AG

    Abstract: Tetrahydro-pyrone-2,4-diones of formula (I): (where R1 is H or lower alkyl; R2 is H or lower alkyl; R3 is 1-10C alkyl or alkenyl opt. substd. by phenyl, carbonyl and/or carbonyl protected against nucleophilic attack, or phenyl, and R4 is H, lower alkyl or phenyl, or R3 and R4 are linked so as to form a 5-8C cycloaliphatic ring), e.g., 4-keto-6-(2-n-butyl-1,3-dithia-2-yl)-tetrahydro-alpha-pyrone, are prepd. by reacting the dianion of an alpha-R1-gamma-R2-acetoacetic acid ester (II) with a carbonyl cpd. of formula: R3R4CO (III) at below-30 degrees C, pouring the reaction mixt. into water, and isolating (I) in a conventional manner. (I) are inters, for natural prodts. such as kawain and pestalotin. High yields are obtd.

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