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3. Journal Coverage by the Major Chemical Title and Abstract Publications

Author

Kiehlmann, Eberhard

Abstract

The journal coverage provided by Chemical Titles,'' Current Contents,'' Science Citation Index,'' Chemischer Informationsdienst,'' and Index Chemicus'' is discussed and compared with the CASSI list of the thousand primary journals most frequently cited by Chemical Abstracts.'' (10 references) (Author/NH)

Published
1972

4. Organization and Efficient Manual Searching of the Major Chemical Title and Abstract Publications

Author

Kiehlmann, Eberhard

Abstract

Science Citation Index'' and several new Chemical Abstracts''' indexes are discussed as effective tools for retrospective literature work and a comparison is made of the features of Chemischer Informationsdienst,'' Index Chemicus,'' Chemical Titles,'' and Current Contents'' as the main sources of current chemical information. (9 references) (Author/SM)

Published
1973

11. Epimerization, transacylation and bromination of dihydroquercetin acetates; synthesis of 8-bromodihydroquercetin.

Author

Kiehlmann, Eberhard and Szczepina, Monica G.

Abstract

Dihydroquercetin ( dhq) and its 3-acetate react with acetic anhydride in the absence of a base catalyst to yield mixtures of partially acetylated products. Three new esters were characterized by NMR spectroscopy as dhq 3,7,3′-triacetate, 3,7,4′-triacetate and 5,7,3′,4′-tetraacetate. At its melting point neat dhq 3,7,3′,4′-tetraacetate is partially converted to dhq 3,3′,4′-triacetate and dhq pentaacetate by intermolecular acetyl transfer. Dhq 7,3′,4′-triacetate yields exclusively dhq 3′,4′-di- and 3,7,3′,4′-tetraacetate under these conditions. The acetylation/deacetylation reactions are accompanied by partial epimerization: 3 new acetates with 2,3- cis stereochemistry ( dhq 3-, 3,7,3′,4′-tetra- and penta -) were identified. Dhq and its 3,7,3′,4′-tetraacetate undergo regiospecific dibromination at C-6 and C-8 with excess N-bromosuccinimide in polar solvents, and 6,8-dibromo- dhq can be regioselectively debrominated to 8-bromo- dhq with sodium sulfite. [ABSTRACT FROM AUTHOR]

Published
2011
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21. Alkaline methanolysis of 1,1,1-trichloro-2-hydroxy-4-alkanones

Author

Kiehlmann, Eberhard, Wells, J. I., and Reeve, Wilkins

Abstract

Derivatives of the carboxylic acids RCOCH2CH(OCH3)COOH and RCOCH=CHCOOH (R = Me, i-Bu, or tert-Bu) have been identified among the major methanolysis products of three 1,1,1-trichloro-2-hydroxy-4-alkanones, RCOCH2CH(OH)CCl3. In addition, β-methoxy esters RCOCH(OCH3)CH2COOCH3are obtained if hydrogen atoms are present at the alkyl carbon directly attached to the carbonyl group (R = Me or i-Bu). 1,1,1-Trichloro-2-hydroxy-4-pentanone (1) yields the known methyl 5-chloro-2,4-pentadienoate (9) as a minor by-product. An α,α-dichloro epoxide (15) is postulated as the key intermediate in the methanolysis mechanism leading to the β-methoxy esters.

Published
1976
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