Coumarin reference compounds

R] (a) Hauser, C. R. Swamer, F. W. Adams, J. T. Org. React. 1954, 8, 59. [R] (b) Ellis, G. P., Chromenes, Chromanones, and Chromones from The Chemistry of Hetereocylic Compounds, Weissberger, A. and Taylor, E. C., eds John Wiley Sons, 1977, vol. 31, New York, p.495. Note The author in the former reference refers to the formation of chromones, coumarins, and flavones as the Kostanecki acylation while the latter author calls the formation of chromones and coumarins the Kostanecki-Robinson reaction. 

Arcmatic compounds phenols, phenolic acids, cinnamic acid derivatives, coumarins, flavonoids, quinones, and tannins, all of which are aromatic compounds, comprise the largest group of secondary plant products. They are often referred to as "phenolics" and have been identified as allelopathic agents in more instances than all of the other classes of compounds combined 5). 

The distribution of sesquiterpene lactones often is referred to as an indication of affinity between the Asteraceae and the Apiaceae (Hegnauer, 1977). These two families share polyacetylenes, coumarins, and flavonoids, as well as other types of compounds. The stereochemical features of the sesquiterpene lactones found in these families provide additional support for the relationship (Holub et al, 1987). 

The proof of structure of many of the coumarins in the Tables has come as a result of the ingenious and enlightened use of a variety of organic chemical techniques by many researchers and the reader is referred to the particular references quoted for each compound. Assignment of structure to a new coumarin is a two-fold problem of initially identifying the different substituent groups and then allocating these to their correct position on the coumarin nucleus. 

The major part of this review concerns chromones which possess a carboxyl or related group at C-2 but a few derivatives of the 3-carboxylic acids are known and discussed. Compounds in which the heterocyclic oxygen or the pyrone carbonyl oxygen is replaced by sulphur are also mentioned. The chemistry of chromones has been reviewed up to 1948 [1] and a survey (without references) of the synthesis of coumarins and chromones of therapeutic interest appeared in 1970 [2], Naturally-occurring chromones are covered in a chapter of a book by Dean [3]. The chromone-2- and -3-carboxylic acids have not been reviewed previously, although an early review of chromones [4] contains a short section on chromone carboxylic acids. 

Abstract The synthesis, reactivity and applications of flnorinated a- and y-pyrones, chromones and coumarins are reviewed. The literature data clearly indicate that these heterocycles are very attractive building blocks for the synthesis of various heterocyclic compounds containing the R group. This chapter reviews the significant advances in this area, highlighting new and interesting trifluoromethylated derivatives and their novel transformations. The bibliography includes 204 references. 

Novel calix[4]arene-based anion sensor 334 with two coumarin units attached via amido functions acting also as binding sites was described. This compound may be considered as a potential fluorescent chemosensor for F. Reference calixarene 335 was also synthesized and its 1,3-alternate conformation was deduced from the H NMR spectrum [192] (Scheme 107). 

The Report this year shows some changes. The section on pyrones and coumarins has been omitted, and a new section on the synthesis of thioesters and related compounds is included. Cross references in the Report refer to the corresponding chapters in earlier volumes, i.e. (1, 236) refers to reference 236 in Chapter 3 of Volume 1, (2, 236) to Chapter 3 of Volume 2, and (3,236) to the present chapter. 

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