Coumarin derivatives, chemical

Brand Name(s) Coumadin, antoven Chemical Class-. Coumarin derivative... 

In addition to the presence of natural coumarin derivatives, phytochemical analysis found that dong quai also contains ferulic acid and osthole as ingredients. Ferulic acid was reported to have antithrombotic activity (38). Similarly, study using the closely related Angelica pubescens also found osthole to be antithrombotic (39). These two chemical constituents exert their antithrombotic effects by interfering with different pathways responsible... 

Table 5.37. Structures and 13C Chemical Shifts (<5C in ppm) of Natural Coumarin Derivatives [635],...

Table 536. 13C Chemical Shifts (Sc in ppm) of Monosubstituted Coumarin Derivatives. 

Fig. 7 Chemical structures and calculated logP values of 3-formylchromone and coumarin derivatives (FC1-16)...

Choi ES, Noh MJ, Yoo KP. Effect of functional groups on the solubilities of coumarin derivatives in supercritical carbon dioxide. In Abraham MA, Sunol AK, eds. Supercritical Fluids Extraction and Pollution. Washington, DC American Chemical Society, 1997 110-118. 

Much more pronounced effects were reported by Sojka (15) who compared the l3C chemical shifts of a number of coumarin derivatives in chloroform and in 96% sulphuric acid and by Yufit et al. (74) for some 4,7-diaminocoumarins in 10-25% and 40% sulphuric acid solutions. For coumarin itself the differences are C-2, 13.2 C-3, -5.3 C-4, 16.5 C-5, 4.3 C-6, 7.1 C-7, 8.0 C-8, 3.4 C-9, 0.6 and C-10, 3.7 ppm, when the data of the chloroform spectrum are subtracted from those in sulphuric acid (15). Even the j(C,H) values are sensitive, and vary up to 16 Hz. These dramatic effects are explained by protonation of the carbonyl group and by considering a different balance of mesomeric forms of the molecule. They are not constant in their magnitude, however, when coumarin is substituted in different positions. 

Tables 5-13 contain 13C chemical shifts of the coumarin moiety and some other atoms in the molecular backbones of 876 coumarin derivatives. They are arranged according to the substitution patterns and basic molecular systems compiled in Fig. 18 below. Therefore, compound chiffres have been composed in such a way that the basic system (initial letter) and the substitution pattern (numbers after the letter) can be read directly the number after the hyphen indicates the hierarchical order which is given by the nature of that atom in a substituent which is directly connected to the coumarin moiety sequencing according to the Cahn-Ingold-Prelog rule. For example, D348-1 is a trisubstituted coumarin (D) carrying substituents at C-3, C-4 and C-8 (348 3-Br, 4-OH, 8-Me). Since bromine has the top position of all substituents at C-3 in all 3,4,8-trisubstituted coumarins listed, the compounds is the first entry (-1). The only exception from this rule appears in di- and tri-coumarins where the numbers after the letter indicate the positions at which the two (three) coumarin systems are connected.

There are two different chemical classes of orally active anticoagulants, namely coumarin derivatives and 1,3-indandiones. 

Novobiocin does not belong to any particular chemically defined group of antibiotics although there are a number of groupings in e molecule which may be related to specific effects. The antibiotic is a coumarin derivative (I) (see p. 40) and has been shown to inhibit oxidative phosphorylation in Mycobacterium phlei [82]. A vitamin K compound is necessary for electron transport in this organism, and both novobiocin-induced inhibition of electron transport and inhibition of growth are reversed by vitamin K. 

The chemical principles applied in the labelling of acidic functions using fluorescent coumarin derivatives were also used in conjunction with other fluorophores. The conditions of the alkylation reactions are therefore the same. Consequently, these reagents suffer equally from a lack of selectivity usually all acidic functions (carboxyl, phenol, thiol, imide and hydroxyl) can be brought to reaction. 

The contradictory observations on the toxicity of coumarin stimulated our research into closely related coumarin derivatives in biochemical-pharmacological studies. Considering the limited information available in the various reviews on the biological properties of these compounds, the main emphasis in this paper will be placed on this aspect. It has been considered important to discuss the chemical structure-biological activity relationship of simple coumarins, coumarin anticoagulants, light sensitisers, aflatoxins, and related isocoumarin... 

Even though the route A could provide a variety of 4-substituted coumarins, a drawback to this procedure is that some of the organometallic reagents are not readily available. Therefore, in spite of the present methodologies, there is still a need to explore a versatile synthetic methodology for the construction of a chemical library of 4-substituted coumarin derivatives. We considered the alternative route to the synthesis of 4-substituted coumarins, depicted by route B in Scheme 3.7. We assumed that this route could provide a versatile vray of introducing a variety of different substituents at the 4-position of coumarin. The direct preparation and application of 4-coumarinylzinc bromide represents a novel and versatile approach to many new substituted coumarins [113]. 

This procedure facilitated the modihcation and purification of coumarin derivatives, but it was restricted to one-dimensional chemical diversity. Lam and coworkers overcame this limitation and improved the overall synthetic efficiency using 7-fluoro-4-methyl-6-nitrocoumarin-3-carboxylic acid as a scaffold with three potential derivatization points (Figure 14.5). After loading the carboxyhc acid onto a Rink amide resin, the aryl fluoride underwent aromatic nucleophihc substitution and the nitro group was reduced to render an additional heterocycfic ring that could incorporate further diversity. This versatile synthetic route yielded a wide spectrum of coumarin dyes, such as imidazocoumarins, lactam coumarins, and thioimidazocoumarins. ... 

Many chemical compounds have been described in the Hterature as fluorescent, and since the 1950s intensive research has yielded many fluorescent compounds that provide a suitable whitening effect however, only a small number of these compounds have found practical uses. Collectively these materials are aromatic or heterocycHc compounds many of them contain condensed ring systems. An important feature of these compounds is the presence of an unintermpted chain of conjugated double bonds, the number of which is dependent on substituents as well as the planarity of the fluorescent part of the molecule. Almost all of these compounds ate derivatives of stilbene [588-59-0] or 4,4 -diaminostilbene biphenyl 5-membeted heterocycles such as triazoles, oxazoles, imidazoles, etc or 6-membeted heterocycles, eg, coumarins, naphthaUmide, t-triazine, etc. 

In detergent perfumes, the stabiUty of vanillin is not always certain. It depends on the association made with other raw materials, eg, with patchouli, frankincense, cloves, most of the animal notes, and such chemicals as amyl saUcylate, methyl ionones, heflotropin, gamma undecalactone, linalool, methyl anthrarulate, benzyl acetate, phenyl ethyl alcohol, cedar wood derivatives, oak mosses, coumarin, benzoin. Pern balsam, and cistus derivatives. In some cases, these mixtures can cause discoloration effects. 

The isoprene-derived molecule whose structure is shown here is known alternately as Coumarin and warfarin. By the former name, it is a widely prescribed anticoagulant. By the latter name, it is a component of rodent poisons. How can the same chemical species be used for such disparate purposes The key to both uses lies in its ability to act as an antagonist of vitamin K in the body. 

---