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Sodium ester reduction with

The compound has also been synthesized from 3-methylindoleacetic acid via the ethyl ester, reduction with sodium and alcohol to the ethanol, to the ethyl bromide with PBr3 in Et20, to the product (2-Me-DMT) with dimethylamine. The reported mp of the free base is 97-98 °C. [Pg.174]

Further, if the ester reduction with sodium (Na) metal is carried out in the absence of a hydrogen donor, two equivalents of ester condense with each other to produce an a-hydroxyketone (an acyloin) (Scheme 9.112). As shown in Scheme 9.112, when the acyloin condensation reaction is carried out on ethyl butanoate with sodium (Na) metal in diethyl ether [(CH3CH2)20] at reflux, 4-hydroxy-5-octanone is produced (in about 70% yield) by what appears to be a series of one-electron transfer processes. [Pg.867]

Extremely dry (or super-dry ) ethyl alcohol. The yields in several organic preparations e.g., malonic ester syntheses, reduction with sodium and ethyl alcohol, veronal synthesis) are considerably improved by the use of alcohol of 99-8 per cent, purity or higher. This very high grade ethyl alcohol may be prepared in several ways from commercial absolute alcohol or from the product of dehydration of rectified spirit with quicklime (see under 4). [Pg.167]

Reduction with sodium in alcohol was unsuccessful (54). The introduction of lithium aluminium hydride has provided an elegant method for the reduction of thiazole esters to hydroxythiazoles for example, ethyl 2-methyl-4-thiazolecarboxylate (11 with lithium aluminium hydride in diethyl ether gives 2-methyl-4-(hydroxymethyl)thiazole (12) in 66 to 69% yield (Scheme 7) (53),... [Pg.524]

An aiyl methane- or toluenesulfonate ester is stable to reduction with lithium aluminum hydride, to the acidic conditions used for nitration of an aromatic ring (HNO3/HOAC), and to the high temperatures (200-250°) of an Ullman reaction. Aiyl sulfonate esters, formed by reaction of a phenol with a sulfonyl chloride in pyridine or aqueous sodium hydroxide, are cleaved by warming in aqueous sodium hydroxide. ... [Pg.168]

On reduction with sodium amalgam the acid adds on two atoms of hydrogen the resulting amorphous aeid yields a crystalline dimethyl ester, C2iH2gOgN2, colourless prisms, m.p. 143-7° dec.). On hydrogenation in presenee of platinic oxide as catalyst 2 mols, of hydrogen are absorbed to form the acid, CjgHjgOgNj, colourless prisms, [ajo - -17-7° (HjO). On oxidation with chromic acid the Cjg acid is converted into Wieland s Ci7 acid and Hanssen s Cjg acid. ... [Pg.567]

A benzyl carbonate was prepared in 83% yield from the sodium alkoxide of glycerol and benzyl chloroformate (20°, 24 h). It was also prepared by a lipase-catalyzed ester exchange with allyl benzyl carbonate. It is cleaved by hydrogenolysis (H2/Pd-C, EtOH, 20°, 2 h, 2 atm, 76% yield) and electrolytic reduction (—2.7 V, R4N X, DMF, 70% yield). A benzyl carbonate was used to protect the hydroxyl group in lactic acid during a peptide synthesis." ... [Pg.186]

The final stages of the successful drive towards amphotericin B (1) are presented in Scheme 19. Thus, compound 9 is obtained stereoselectively by sodium borohydride reduction of heptaenone 6a as previously described. The formation of the desired glycosida-tion product 81 could be achieved in dilute hexane solution in the presence of a catalytic amount PPTS. The by-product ortho ester 85 was also obtained in approximately an equimolar amount. Deacetylation of 81 at C-2, followed sequentially by oxidation and reduction leads, stereoselectively, to the desired hydroxy compound 83 via ketone 82. The configuration of each of the two hydroxylbearing stereocenters generated by reduction of carbonyls as shown in Scheme 19 (6—>9 and 82->83) were confirmed by conversion of 83 to amphotericin B derivative 5 and comparison with an... [Pg.446]

In this section primarily reductions of aldehydes, ketones, and esters with sodium, lithium, and potassium in the presence of TCS 14 are discussed closely related reductions with metals such as Zn, Mg, Mn, Sm, Ti, etc., in the presence of TCS 14 are described in Section 13.2. Treatment of ethyl isobutyrate with sodium in the presence of TCS 14 in toluene affords the O-silylated Riihlmann-acyloin-condensation product 1915, which can be readily desilylated to the free acyloin 1916 [119]. Further reactions of methyl or ethyl 1,2- or 1,4-dicarboxylates are discussed elsewhere [120-122]. The same reaction with trimethylsilyl isobutyrate affords the C,0-silylated alcohol 1917, in 72% yield, which is desilylated to 1918 [123] (Scheme 12.34). Likewise, reduction of the diesters 1919 affords the cyclized O-silylated acyloin products 1920 in high yields, which give on saponification the acyloins 1921 [119]. Whereas electroreduction on a Mg-electrode in the presence of MesSiCl 14 converts esters such as ethyl cyclohexane-carboxylate via 1922 and subsequent saponification into acyloins such as 1923 [124], electroreduction of esters such as ethyl cyclohexylcarboxylate using a Mg-electrode without Me3SiCl 14 yields 1,2-ketones such as 1924 [125] (Scheme 12.34). [Pg.281]

The first conversion of protoberberines to phthalideisoquinoline alkaloids was achieved by Moniot and Shamma (88,89). 8-Methoxyberberinephenol-betaine (131), derived from berberine (15) (Section III,B,2), is an attractive compound having a carboxyl group masked as an imino ether in ring B. The masking was uncovered by hydration with water-saturated ether to furnish dehydronorhydrastine methyl ester (367) (Scheme 65). On N-methylation (68%) and subsequent sodium borohydride reduction (90%), 367 provided (+ )-/ -hydrastine (368) and ( )-a-hydrastine (369) in a 2 1 ratio. Compound 367 was converted to dehydrohydrastine (370), which also afforded 368 and 369 by catalytic hydrogenation. [Pg.195]

Keto acids can be dehydrated to enol lactones (Section III,A,1). They may also undergo esterification with alcohols e.g., /V-methylhydrasteine (104) in methanol at room temperature gave the expected keto ester 126 (R + R = CH2, R1 = CH3) (5,87). Sodium borohydride reduction of keto acid 104 supplies the saturated y-lactone 132 identical with that obtained from enol lactone 98 (5). [Pg.270]

The structure of narlumidine (119) was established by Dasgupta et al. (117,119) on the basis of spectral data, particularly by comparison with spectra of bicucullinine (108), and also on chemical grounds. On hydrolysis followed by oxidation-methylation, narlumidine (119) was converted to ester 147, which was also obtained from 108 by N.O-methylation. Sodium borohydride reduction gave lactone 145, identical to the lactone obtained from 108. [Pg.274]

We have seen similar radical anions generated from ketones in pinacol reduction with sodium or magnesium (p. 218), and also from esters with sodium in the acyloin condensation (p.218). [Pg.307]

Aminoacetal has been prepared by the action of ammonia on haloacetals,8 4 6 6 7-8 9 by the reduction of nitroacetal using sodium in boiling alcohol,10 and by the reduction of glycine ester hydrochloride with sodium amalgam.11... [Pg.4]

Dihydrocorynantheine was obtained via similar steps from normal cyanoacetic ester 319 (172). Stereoselective transformation of the alio cyanoacetic ester 315 to the normal stereoisomer 319 was achieved by utilizing a unique epimerization reaction of the corresponding quinolizidine-enamine system (174). Oxidation of alio cyanoacetic ester 315 with lead tetraacetate in acetic acid medium, followed by treatment with base, yielded the cis-disubstituted enamine 317, which slowly isomerized to the trans isomer 318. It has been proved that this reversible eipmerization process occurs at C-15. The ratio of trans/cis enamines (318/317) is about 9 1. The sodium borohydride reduction of 318 furnished the desired cyanoacetic ester derivative 319 with normal stereo arrangement. The details of the C-15 epimerization mechanism are discussed by B rczai-Beke etal. (174). [Pg.198]

Tetracyclic keto ester 467, prepared earlier (253), was treated with the anion of diethyl methoxycarbonylmethylphosphonate in dimethylformamide. The reaction supplied the unsaturated ester 492, which was catalytically hydrogenated to diester 493. Dieckmann condensation of 493 yielded two nonenolizable keto esters (494 and 495), which could be separated by fractional crystallization. Sodium borohydride reduction of 18a-methoxyyohimbinone (494) gave two alcohols (496 and 497) in a ratio of about 10 1 at the same time, reduction of 180-methoxyyohimbinone (495) furnished another two stereoisomeric alcohols (498 and 499) in approximately equal amounts. Demethylation of the four stereoisomers (496-499) resulted in the corresponding 18-hydroxyyohimbines (500-503)... [Pg.230]

ALDEHYDES BY OXIDATION OF TERMINAL OLEFINS WITH CHROMYL CHLORIDE 2,4,4-TRIMETHYL-PENTANAL, 51, 4 ALDEHYDES FROM ACID CHLORIDES BY MODIFIED ROSENMUND REDUCTION 3,4,5—TRIMETHOXYBENZ-ALDEHYDE, 51, 8 ALDEHYDES FROM ACID CHLORIDES BY REDUCTION OF ESTER MESYLATES WITH SODIUM BOROHY-DRIDE CYCLOBUTANECARBOXAL-DEHYDE, 51, 11... [Pg.54]

Vigorous reduction with metallic sodium (and a little alcohol) converts esters into the corresponding primary alcohols (Bouveault) ... [Pg.146]


See other pages where Sodium ester reduction with is mentioned: [Pg.388]    [Pg.220]    [Pg.311]    [Pg.512]    [Pg.29]    [Pg.84]    [Pg.133]    [Pg.279]    [Pg.531]    [Pg.424]    [Pg.456]    [Pg.91]    [Pg.190]    [Pg.387]    [Pg.204]    [Pg.1025]    [Pg.49]    [Pg.251]    [Pg.451]    [Pg.7]    [Pg.499]    [Pg.242]    [Pg.251]    [Pg.220]    [Pg.379]    [Pg.312]    [Pg.140]    [Pg.482]   
See also in sourсe #XX -- [ Pg.388 ]




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