Condenser analogy

Four different synthetic methods leading to azetidones and condensed analogs have been described. These are discussed below in relation to the types of organometallic complexes used as reactants or envisaged as intermediates. 

Reaction of 3-Lithiomethyl-2-methyl-l-phenylpyrazolin-5-one with 6 A New General Method for the Synthesis of 1,2-Disubstituted Indazolones and Their Condensed Analogs (Type III, 3a Model)... 

The probable configuration of isosucrose was systematically discussed by Georg,who thought that the yield was much greater when the beta anomer, rather than the equilibrium mixture or the alpha anomer, of 2,3,4,6-tetraacetyl-D-glucose was used in the condensation. Analogy with tetraacetyl-D-fructopyranosyl chloride, which yielded the acetylated... 

There has been considerable interest in hydroxy-3,3 -bipyridines and 3,3 -bipyridinones. Following from some very early work on the oxidation of citrazinic acid (2,6-dihydroxypyridine-4-carboxylic acid), which was considered to give some polyhydroxy-3,3 -bipyridines, it has been shown that the 3,3 -bipyridinone 59, a product of the hydrolysis of a natural blue pigment from Corynehacterium insidiosum, is obtained by oxidation of 2-hydroxy-5-aminopyridine (60) or 2,6-dihydroxypyridine-4-carboxylic acid 61) 80,83 similar oxidation of 2,6-dihydroxy-3-aminopyridine-4-carboxylic acid affords the natural product indigoidine (20). Numerous related oxidative condensations have been reported subsequently. Cyano-acetamide condensations analogous to those discussed in the synthesis of 2,3 -bipyridines afford, for example, the cyano-substituted 3,3 -bipyridinone 62 588 v, lereas condensation of 3-pyridylacetonitrile with ethyl phenyl-propiolate and ethanol affords compound 63. To complete the section on... 

A., 297, 92 B., 36, 3678 38, 714, 1934.) Both assumptions coincide equally well with the fact that fatty acid esters do not condense analogously to the above, with secondary and tertiary alkyl groups. 

An early structural modification of FA and AP involved alkylation at C-9 and/or N-10. 10-MethylFA (447) [197] was prepared by reaction of 2,4,5-triamino-6-hydroxypyrimidine, 2,3-dibromopropionaldehyde and diethyl p-methylaminobenzoylglutamate (35), followed by alkaline hydrolysis (the Waller condensation). Analogous utilization of 2,2,3-trichlorobutyraldehyde and the requisite p-(JV-substituted amino)benzoylglutamate furnished (448a-c) (Scheme 3.88) [198]. The preparation of (450) by condensation of 2,4,5,6-tetraaminopyrimidine and the a-ketoacetal (449) was reported without details (Scheme 3.89) [199],... 

Nitroazoles are compounds of very considerable commercial and chemotherapeutic importance. The introduction of metronidazole, dimetridazole, and their condensed analogs has stimulated much synthetic chemistry of nitroazoles resulting in the discovery of a number of compounds that are important for the treatment of different human and/or animal diseases. 

Chapters 1 and 2 give comprehensive data on the preparation methods of all known C- and iV-nitroderivatives of five-membered azoles and their condensed analogs. This book focuses on the nitration reaction, one of the main synthetic routes to nitroazoles. General information on the theory of nitration is given prior to the chapter covering synthetic methods. A separate section in the monograph is given to the special class of nitroazoles - polynitroazoles. 

All this provoked us to write a monograph considering from unified positions all the literature available and our own data concerning the methods of synthesis, structure, properties, and application of C- and N-nitroderivativcs of azoles and their condensed analogs. 

Nunes proposed also a second mode of biogenesis, based on L-threonine (Scheme 6). This scheme makes first use of an aldol condensation, analogous to the early proposal of Leete, followed by esterification to the lactone. In both schemes the last step is a selective methylation of N by S-adenosyl-methionine. 

Diphenyl-1,2-dithiolium ion leads to 3-amino-1,3-diphenylprop-2-ene-l-thiones when reacted with methylamine, ethylamine, ben-zylamine, 2-aminoethanethiol, piperidine,aniline, toluidines, anisi-dines, and chloranilines. With dimethylamine a double condensation, analogous to the one shown in Eq. (15), occurs. ... 

In the presence of a strong base, e.g., lactam anions, the imide groups containing at least one ct-hydrogen undergo a Claisen type condensation analogous to the condensation of esters or ketones [121, 125], viz. 

Figure 7.1. Continuous single-stage equilibrium separation, (a) Flash vaporization. (Adiabatic flash with valve isothermal flash without valve when Tv is specified. (6) Partial condensation. (Analogous to isothermal flash when Ty is specified.

The 4-(chloromethyl)isoxazole 13, which is readily accessible from 3,5-dimethyloxazole, serves as a C4-building-block in annulations to cycloalkanones (isoxazole annelation according to Stork). The primary step is alkylation leading to product 14, a masked triketone. On hydrogenation, the isoxazole ring is reductively opened and cyclization via the enaminone 15 leads to the enamine 16. On treatment with sodium hydroxide, this is converted into the bicycloenone 17 by hydrolysis, acid fission of the y dicarbonyl system and an intramolecular aldol condensation (analogous to a Robinson annu-lation) ... 

Aldol condensations analogous to the formose reaction have been utilized to synthesise mixtures of trioses, tetroses, pentoses, and hexoses from 3-oxo compounds. The same paper describes the synthesis of hexoses from barium hydroxide treatment of acrolein dibromide. 

The map in Figure 4.20 shows how the operating temperature affects the partial pressure of benzene in the effluent. This map is a design tool for our condenser analogous to the equations we developed as design tools in the previous chapter. More on graphical design tools will be presented later. 

In scanning electron microscopy (SEM), an electron beam (primary electrons) is directed to a specimen surface by beam condensers (analogous to lenses with a light... 

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