Diethyl carbonate, condensation with

In a reaction related to the mixed Claisen condensation nonenolizable esters are used as acylatmg agents for ketone enolates Ketones (via their enolates) are converted to p keto esters by reaction with diethyl carbonate... 

In an altogether different type of approach, the hydrazone is formed in situ as a lithium salt. Wilson et al. (80JHC389) described this approach in the one-pot synthesis of 5-aryl-2-phenylpyrazol-3-ones 72a-f from the corresponding hydrazones 65a-f (Scheme 20). The latter were obtained by condensing ketones 64a-f with phenylhydrazine. Treatment of hydrazones 65a-f with n-butyllithium in dry THF, followed by the addition of half a molar equivalent of diethyl carbonate 67 and then quenching the reaction mixture with hydrochloric acid, produced pyrazol-3-ones 72a-f, along with products 71. The yields of the products 72 are in the range 22-97%. Four intermediates—66a-f, 68a-f, 69a-f, and 70a-f— were proposed for this reaction. 

Cyclization of 21 by means of diethyl carbonate gives the corresponding aminooxazolidone (24). This compound is then condensed with benzaldehyde to Shiff base (25). An exchange reac-... 

In a scheme intended to produce a more highly substituted oxazolidone, epichlorohydrin is condensed with morpholine in the presence of strong base to give the aminoepoxide, 27. Ring opening of the oxirane by means of hydrazine gives the hydroxy-hydrazine (28). Ring closure with diethyl carbonate leads to the substituted oxazolidone (29). Condensation with 18 affords furaltadone (30). ... 

Further work in this area showed that only one of the cou-marin rings was needed for biologic activity. Condensation of the hydroxyacetophenone, 4, with diethyl carbonate affords 4-hydroxycoumarin (2). The reaction may involve the 3-ketoester (5) cyclization of this would afford 2. Alternately, the reagent may first give the 0-acyl derivative cyclization as above will give the same product. Michael condensation of the coumarin with benzalacetone (6) affords the anticoagulant warfarin (named after its place of origin Wisconsin Alumni Research Foundation,... 

Cyclooctanone, condensation with diethyl carbonate, 47, 20 Cyclopentadiene, adduct formation with 1,2,3-benzothiadiazole 1,1-diox-ide, 47, 8... 

MalONIC ACID, ETHYLHYDROXY, DIETHYL ESTER, BENZOATE, 45, 37 Mfsitaidehydf, 47, 1 Mesitylcne, condensation with dichloro methyl methyl ether, 47, 1 Methalljl chloride in alkylation of 2,4-pentanedione with potassium carbonate, 47, 87... 

Notable examples of general synthetic procedures in Volume 47 include the synthesis of aromatic aldehydes (from dichloro-methyl methyl ether), aliphatic aldehydes (from alkyl halides and trimethylamine oxide and by oxidation of alcohols using dimethyl sulfoxide, dicyclohexylcarbodiimide, and pyridinum trifluoro-acetate the latter method is particularly useful since the conditions are so mild), carbethoxycycloalkanones (from sodium hydride, diethyl carbonate, and the cycloalkanone), m-dialkylbenzenes (from the />-isomer by isomerization with hydrogen fluoride and boron trifluoride), and the deamination of amines (by conversion to the nitrosoamide and thermolysis to the ester). Other general methods are represented by the synthesis of 1 J-difluoroolefins (from sodium chlorodifluoroacetate, triphenyl phosphine, and an aldehyde or ketone), the nitration of aromatic rings (with ni-tronium tetrafluoroborate), the reductive methylation of aromatic nitro compounds (with formaldehyde and hydrogen), the synthesis of dialkyl ketones (from carboxylic acids and iron powder), and the preparation of 1-substituted cyclopropanols (from the condensation of a 1,3-dichloro-2-propanol derivative and ethyl-... 

Cyclooctanol, oxidation by chromium trioxide to cyclooctanone, 45, 29 Cyclooctanone, 46,28 condensation with diethyl carbonate, 47,20... 

Kuethe et al. reported the synthesis of the tjipanazoles D (359), I (360), B (369), and E (370) starting from the nitro derivative 1496 (796). This route involves the synthesis of 2,2 -bisindoles, followed by a two-carbon insertion through condensation with (dimethylamino)acetaldehyde diethyl acetal to afford the indolocarbazole ring. 

A. Ethyl hydrazinecarboxylate. To 100 g. (97 ml., 2.0 moles) of 100% hydrazine hydrate, contained in a 1-1. round-bottomed Hank, iH added 236 g. (243 ml., 2.0 moles) of diethyl carbonate (Note I). The flask is fitted with a calcium chloride-containing drying tube and is shaken vigorously to mix the two liquids. After about 5 minutes, the milky emulsion becomes warm, and shaking is continued until a clear solution is obtained (approximately 20 minutes). The flask is equipped with a reflux condenser fitted with a calcium chloride-containing drying tube and is heated on a steam bath for 3.5 hours. The reaction mixture is transferred to a 500-ml. round-bottomed flask and is... 

The reactivity of amino functions on diazotization and condensation with dimethylformamide dimethyl acetal has been discussed in CHEC-II <1996CHEC-II(7)431>. The diamine 220 is readily converted into a variety of tricyclic pyrazolo[3,4-r/ pyrimidines under a variety of conditions <2004T5093>. Thus with chloroacetyl chloride the chlor-oacetyl derivative 221 was formed. This could not be further cyclized into 222. Refluxing 220 with diethyl oxalate afforded 223 while 224 was formed when the reaction was conducted at 40 °C. Treatment of 224 with POCI3 afforded 223. Reacting 220 with carbon disulfide afforded 225 (Scheme 14) <2004T5093>. 

As rapidly as possible, after removal of the ethanol, the flask is fitted with a rubber-sealed stirrer, a dropping funnel, a distilling head containing a thermometer, and a condenser arranged for distillation into a flask protected by a calcium chloride tube. There are then added 300 ml. of dry diethyl carbonate, 80 ml. of dry toluene, and 58.5 g. (0.50 mole) of phenylacetonitrile (Note 2). The flask is heated, with good stirring, and the cake of sodium ethoxide soon dissolves. When distillation has started, dry toluene is added dropwise at about the same rate that the distillate is collected. Approximately 200-250 ml. of toluene should be added in a period of 2 hours (Note 3) while stirring and distillation are continued. 

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