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Phosphorus Chloride enols

A thioamide of isonicotinic acid has also shown tuberculostatic activity in the clinic. The additional substitution on the pyridine ring precludes its preparation from simple starting materials. Reaction of ethyl methyl ketone with ethyl oxalate leads to the ester-diketone, 12 (shown as its enol). Condensation of this with cyanoacetamide gives the substituted pyridone, 13, which contains both the ethyl and carboxyl groups in the desired position. The nitrile group is then excised by means of decarboxylative hydrolysis. Treatment of the pyridone (14) with phosphorus oxychloride converts that compound (after exposure to ethanol to take the acid chloride to the ester) to the chloro-pyridine, 15. The halogen is then removed by catalytic reduction (16). The ester at the 4 position is converted to the desired functionality by successive conversion to the amide (17), dehydration to the nitrile (18), and finally addition of hydrogen sulfide. There is thus obtained ethionamide (19)... [Pg.255]

Thus, treatment of the benzamide (35-1) from 2-phenethylamine with phosphorus oxychloride probably results in an initial formation of a transient enol chloride this then cycUzes to (35-2) under reaction conditions. The imine is then reduced with sodium borohydride. Resolution by means of the tartrate salt affords (35-3) in optically pure form. Acylation of that intermediate with ethyl chloroformate leads to carbamate (35-4). Reaction of this last with the anion from chiral quiniclidol (35-5) interestingly results in the equivalent of an ester interchange. There is thus obtained the anticholinergic agent solifenacin (35-6) [40]. [Pg.452]

Dihydralazine (67-3) is the less important of the two phthalazine antihypetensive agents its preparation is however recorded first because of its simplicity. Thus, reaction of phthaUiydrazide (67-1) with phosphorus oxychloride leads to the by now very famihar conversion of the amide functions to enol chlorides (67-2). The displacement of halogen by hydrazine leads directly to the antihypertensive agent dihydralazine (67-3) [76]. [Pg.473]

The particularly good activity against protein kinases of a-aminoquinazoline derivatives is borne out by their activity against both in vitro and in vivo models of human tumors. The examples that follow are but two of a number of compounds from this structural class that have emerged from the focus that has been devoted to this stmctural class. Nitration of the benzoate (78-1) with nitric acid affords the nitro derivative. Hydrogenation converts this to the anthrandate (78-2). In one of the standard conditions for forming quinazolones, that intermediate is then treated with ammonium formate to yield the heterocycle (78-3). Reaction of this last product with phosphorus oxychloride leads to the corresponding enol chloride (78-4). Condensation of this last intermediate with meta-iodoanUine (78-5) leads to displacement of chlorine and the consequent formation of the aminoquinazoline... [Pg.479]

In a similar vein, reaction of the readily accessible xanthine (39-1) with the ubiquitous phosphorus oxychloride affords the enol chloride (39-2). Alkylation of the anion obtained from that product with a base with the chloro deoxy sugar (39-3) leads to the glycosylated product (39-4). Treatment with ammonia selectively replaces the halogen at the 6 position. The protecting groups on the sugar are cleaved in the course of the reaction to afford cladribine (39-4) [41]. [Pg.602]

Many examples exist where the open chain betaine may be quenched by reagents, giving stable phosphorus compounds with P-C1V = 3. When (180) is reacted with acetyl chloride the open chain enol phosphate (181) is formed. Many interesting O- and N-phosphaspirans are also mentioned in (75BSF407). [Pg.535]

In practice the dehydration can be achieved with a broad range of acids or acid anhydrides, such as phosphoric add, phosphorus oxychloride, phosgene (COCI2), and thionyl chloride. An example of the mechanism is shown below for thionyl chloride and involves activation of the amide to imidolyl halide 3.16 then intramolecular attack by the enolic form of the ketone. [Pg.22]

Bromination of acid derivatives is usually carried out not on the acid itself but by converting it to an acyl bromide or chloride, which is not isolated but gives the a-bromoacyl halide via the enol. This used to be done in one step with red phosphorus and bromine, but a two-step process is usually preferred now, and the bromoester is usually made directly without isolating any of the intermediates. We can summarize the overall process like this. [Pg.536]

Selenenyl halides are relatively stable, though moisture sensitive, compounds that are generally prepared by the reactions shown in Scheme 7 and behave as electrophihc selenium species. " They react with ketones and aldehydes via their enols or enolates to afford a-seleno derivatives (e.g. (17) in equation 11). Similar a-selenenylations of /3-dicarbonyl compounds, esters, and lactones can be performed, although the latter two types of compounds require prior formation of their enolates. Moreover, the a-selenenylation of anions stabilized by nitrile, nifro, sulfone, or various types of phosphorus substituents has also been reported (equation 12). In many such cases, the selenenylation step is followed by oxidation to the selenoxide and spontaneous syn elimination to provide a convenient method for the preparation of the corresponding a ,/3-unsaturated compound (e.g. 18 in equation 11). Enones react with benzeneselenenyl chloride (PhSeCl) and pyridine to afford a-phenylselenoenones (equation 13). [Pg.4321]

The nucleophile-accepting acrylamide group in the kinase inhihitor canertinib (154) may lead to covalent binding of that group to sites on the enzyme and thus irreversihle inhihition. The starting quinazolone (147) is available by some scheme such as that above. The carbonyl group is first converted to its enol chloride (148) by means of phosphorus oxychloride. [Pg.180]

The reactions of hexafluoroacetone with trimethylsilyl ethers of enols form 4,4-bis(trifluoromethyl)-l-oxabuta-l,3-dienes (92JPC311). When heated in the presence of tin(II) chloride, the latter are transformed into 4,4-difluoro-3-trifluo-romethylbut-3-en-l-one. Subsequent treatment with sodium hydride leads to 2-fluoro-3-trifluoromethylfuran, while with phosphorus pentasulfide the product is 2-fluoro-3-trifluoromethylthiophene (92JCS(CC)348). Partially fluorinated 1-oxopenta-1,4-diene, derived from hexafluoroacetone, is employed as an intermediate in the syntheses of fluorinated furans (92JCS(CC)349) and thiophenes (92JFC(58)380) (Scheme 9). [Pg.277]

The reaction between tris(trimethylsilyl) phosphite and a perfluoroacyl chloride proceeds without any apparent difficulty to give the predicted phosphonate diester 489 [R = Me3Si, R = CF3 or (CF3)2CH] but the use of longer chain polyfluorinated acyl halides or other heavily halogenated acyl chlorides leads to complications with such substrates, the initially formed acylphosphonate reacts with more phosphorus(III) ester to give the (Z)-enol phosphate 490 (Scheme 47). The halides, XCH2COX (X = Cl or Br) afford only the esters 491 (X = H). ... [Pg.241]

In a modification to the latter procedure, phosphorylation of lithium enolates may be carried out with a phosphorus(III) acid chloride (phosphitylation) and the resultant... [Pg.253]


See other pages where Phosphorus Chloride enols is mentioned: [Pg.551]    [Pg.18]    [Pg.296]    [Pg.322]    [Pg.111]    [Pg.569]    [Pg.34]    [Pg.37]    [Pg.315]    [Pg.262]    [Pg.374]    [Pg.441]    [Pg.474]    [Pg.510]    [Pg.521]    [Pg.556]    [Pg.566]    [Pg.571]    [Pg.587]    [Pg.589]    [Pg.614]    [Pg.668]    [Pg.498]    [Pg.208]    [Pg.103]    [Pg.168]    [Pg.154]    [Pg.125]   
See also in sourсe #XX -- [ Pg.334 ]




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Phosphorus chlorids

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