Steroids steroidal pyrimidines

Bomah and co-workers [99] developed an efficient procedure for the synthesis of ring-A fused [3,2-h]pyrimidines 53 in a steroidal moiety. The novel steroidal pyrimidines were prepared via a solid phase three-component reaction of a 2-hydro-xymethylene-3-keto steroid, an arylaldehyde and ammonium acetate under micro-wave irradiation. This protocol has been applied successfully to the cyclization of bicyclic, monocyclic and acyclic 2-hydroxymethylene ketones with diversely substituted aromatic aldehydes (Scheme 39). 

Note Flavonoids react with the reagent even at room temperature [1] mycotoxins, steroids, purines, pyrimidines, cardiac glycosides and lipids only react on heating [2, 4-6]. Zirconyl sulfate can be used to replace the zirconyl chloride in the reagent this is reported to result in an increase in the sensitivity to certain groups of substances (e.g. cholesteryl esters, triglycerides) [4]. 

Steroids, e.g. cholesterol, triolein, androsterone sugars, e.g. fructose, glucose, ribose amino acids, pyrimidines, purines, alkaloids 110-150°C, 2-12 h Conversion to fluorescent derivatives by heating. [5]... 

Propiolaldehyde diethyl acetal has found numerous synthetic applications in the literature which may be briefly summarized. The compound has been utilized in the synthesis of unsaturated and polyunsaturated acetals and aldehydes by alkylation of metal-lated derivatives, " by Cadiot-Chodkiewicz coupling with halo acetylenes, " and by reaction with organocuprates. Syntheses of heterocyclic compounds including pyrazoles, isoxazoles, triazoles, and pyrimidines have employed this three-carbon building block. Propiolaldehyde diethyl acetal has also been put to use in the synthesis of such natural products as polyacetylenes " and steroids. ... 

The answer is a. (Hardman, p 1302.) Cyclophosphamide, an alkylating agent, reacts with purine and pyrimidine bases of DNA to form bridges and dimers. These products interfere with DNA replication. 5-FU, methotrexate, and 6-thioguanine are anti metabolites, and the steroid prednisone has some tumor-suppressive effects. 

Proteins, Solid, Adsorption of Water on (Eley Leslie). Proteins and Nucleic Acids, Electronic Structure Proteins and Nucleic Acids, Influence of Physical Agents on Purine-Pyrimidine Pairs, Steroids, and Polycyclic Aromatic Carcinogens (Pullman). ... 

Steroids, Purine-Pyrimidine Pairs, and Polycyclic Aromatic Carcinogens (Pullman). ... 

Actinomycetes can metabolize a wide variety of organic substrates, including organic compounds that are generally not metabolized, such as phenols and steroids. They are also important in the metabolism of heterocyclic compounds such as complex nitrogen compounds and pyrimidines [42,49]. The breakdown products of their metabolites are frequently aromatic, and these metabolites are important in the formation of humic substances and soil humus [42,49]. 

The organoselenium compounds, their chemistry, and methods of preparation are discussed in the literature (3,4,7,11,12,14,59). Selenium-containing polymers are of interest because of their semiconducting and plastic properties. The biologically important compounds include selenoaminocarboxylic acids and derivatives, selenium-containing peptides, and selenium derivatives of pyrimidines, purines, cholines, steroids, coenzyme A, and other compounds (4,14). The biochemical and medical aspects and uses of oiganoselenium compounds have also been discussed (13,14,60—62). 

Alkaloids are basic plant natural products that typically have a nitrogen atom as part of a heterocyclic ring system and indeed are classified on this basis. Thus major classes of alkaloids are based on indole, isoquinoline, pyrrolidine, piperidine, pyrrolizidine, quinoline, tropane, quinolizidine or other heterocyclic ring systems. Other alkaloids are basic monoterpenoid, sesquiterpenoid, diterpenoid, steroid, purine, pyrimidine or peptide entities. Some of these compounds are exceptionally toxic [1,6, 7-12]. 

The reaction of many compounds of biological interest with ammonium bicarbonate on thin-layer plates permits detection of 10-100-ng amounts of these compounds [141]. Many compounds in the lipid, steroid, sugar, amino acid, purine, pyrimidine and alkaloid classes can be analyzed in this way (Table 4.26). 

STEROIDS, PURINE-PYRIMIDINE PAIRS AND POLYCYCLIC AROMATIC CARCINOGENS ... 

It is hard to see how the authors can reconcile such different exigencies. As regards the steric factors the third condition renders meaningless the condition of resemblance to steroids. The steroids and the purine-pyrimidine pairs are too different from each other to serve simultaneously as a standard for geometrical analogies. As to the electron transfer factors, we have shown in a series of publications that they are unrelated to the presence or absence of carcinogenic activity in aromatic hydrocarbons.27 >81 24... 

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