Sodium Ethoxide In Ethanol Research Articles

Studies on Cyclic Dipeptides. II. Isomerization among cyclo(-4-Hydroxyprolyl-4-hydroxyprolyl-)s and a Novel Conversion of d-allo-Hydroxyproline to l-Hydroxyproline

Abstract The isomerization among c-l-Hyp-l-Hyp (1), c-l-Hyp-d-aHyp (2) and c-d-aHyp-d-aHyp (3) has been examined in ethanolic sodium ethoxide at 25–78 °C as well as in aqueous solutions at 75–250 °C. At equilibrium state, 1 was predominant and 2 was not found at all in the reaction mixture. By the use of this isomerization reaction and the difference of solubility between 1 and 3, 3 could be converted almost quantitatively to 1. The mixture of 1 and 3 was obtained in good yield directly from d-aHyp or l-Hyp by heating in water or ethylene glycol. 1 was hydrolyzed quantitatively to l-Hyp by acid. Thus, l-Hyp was obtained with the yield of 59% from d-aHyp by combination of preparation, isomerization and acid hydrolysis of cyclic dipeptide.

ChemInform Abstract: SYNTHESIS OF SOME 9‐(INDOL‐3′‐YL)‐XANTHENE DERIVATIVES

AbstractBeim Erhitzen der 1‐, 2‐mono‐ bzw. 1,2‐disubstituierten Indole (I) mit dem Dichlorxanthen (II) in Benzol bilden sich blaue Reaktionsgemische, die bei Zusatz von H2O bzw. Na‐äthylat in Äthanol in 9‐Hydroxy‐ bzw. 9‐Äthoxy‐xanthenderivate, wie (IIIa) bzw. (IIIb) und (IIIc), übergehen.

Side-chain reactions in π-chromium tricarbonyl-complexed arenes IV. Solvent and deuterium isotope effects in E2 reactions of some 2-phenylethyl and 1-phenyl-2-propyl derivatives

The rates and products of elimination with sodium ethoxide in ethanol, and potassium t-butoxide in t-butanol, of chromium tricarbonyl-complexed (2-phenylethyl bromides), (2-phenylethyl tosylates), (1-phenyl-2-propyl bromides), and (1-phenyl-2-propyl tosylates) were determined. Complexation increases the rate of elimination, the size of the effect depending on leaving group, solvent/base system and, to a minor extent structure. The Cr(CO) 3 group increases the olefin percentage when substitution competes with elimination, whereas the relative proportions of the olefin isomers obtained from secondary substrates are practically unchanged whether the ring is complexed or not. Deuterium isotope effects have been measured for the elimination from uncomplexed, complexed and 2-( p-nitrophenyl)ethyl compounds. The magnitude of the isotope effect does not vary appreciably with substituents.

Synthesis of some 9-(Indol-3'-yl)xanthene derivatives

9,9-Dichloroxanthene reacts with 1-substituted, 2-substituted and 1,2-disubstituted indoles to yield blue solids which are converted into 9-(indol-3'-y1)xanthenes by water or by sodium ethoxide in ethanol. With a 3-substituted indole, reaction occurs at the 2-position.

Ionisation rates of β-substituted nitroethanes

Ionisation rates of a series of aliphatic nitro-compounds, YCH2·CH2·NO2, have been measured in aqueous sodium hydroxide and in ethanolic sodium ethoxide. Rectilinear σ*ρ* plots for substituents Me, H, Ph, OH, and EtO with ρ*H2O= 2·07 and ρ*EtOH= 1·88 have been obtained; the β-diphenyl compound, Ph2CH·CH2·NO2 ionises more slowly than the monophenyl compound notwithstanding the expected rate-accelerative effect of the second phenyl group.Solvent and salt effects are discussed in connection with transition states for ionisation.

Elimination and addition reactions. Part XXIII. Mechanisms of elimination in nitro-compounds bearing phenoxy and phenylthio leaving groups

Rates of elimination in 1-nitro-2-phenoxyethane and in 1-nitro-2-phenylthioethanes (PhS·CHY·CH2·NO2; Y = H or Ar) have been measured in ethanolic sodium ethoxide, aqueous sodium hydroxide, and aqueous triethylamine. The phenoxy-compound reacts by rate-determining loss of phenoxide from the carbanion [(E1) anion mechanism], while for the α-arylphenylthio-compounds, ionisation is rate-determining and rate constants agree with predictions made from ionisation rates of model substrates. The simple phenylthio-compound (Y = H) undergoes elimination with a primary deuterium isotope effect of 7·4 but rate constants are larger than predicted for rate-determining ionisation and the E2 mechanism is tentatively assigned.

Stereochemistry and reactivity in interconversions of three- and four-co-ordinate imino-derivatives of sulphur

Optically pure sulphoxides have been converted into N-phthalimidosulphoximides by treatment with N-amino-phthalimide and lead tetra-acetate. Sulphoxides are regenerated in high yields and optical purities on treatment with sodium ethoxide or hydrazine in ethanol and it is suggested that each step in these two-step cycles occurs with retention of configuration at sulphur. No attack occurs at the carbon–carbon double bond in formation of the sulphoximide from p-tolyl vinyl sulphoxide.Reactions of S-vinyl- and of S-β-substituted-ethyl-sulphimides have been briefly investigated in a qualitative evaluation of the activating effects of the sulphonylimino-sulphur group on elimination and addition reactions.

Trans/cis olefin ratios as a function of the leaving group in the reactions of 1-phenyl-2-propyl halides with sodium ethoxide in ethanol

Trans/cis olefin ratios as a function of the leaving group in the reactions of 1-phenyl-2-propyl halides with sodium ethoxide in ethanol

Bridge fission in the bicyclo[4,2,1]nonan-9-one series

Reaction of ethyl endo- and exo-7-tosyloxy-9-oxobicyclo[4,2,1]nonane-1-carboxylates and of ethyl 9-oxobicyclo[4,2,1]non-7-ene-1-carboxylate with ethanolic sodium ethoxide leads by bridge fission to diethyl cyclooctene-1,4-dicarboxylate.

Side-chain reactions in π-chromium tricarbonyl complexed arenes : II. Elimination from (2-phenylethyl tosylate)- and (2-phenylethyl bromide)-chromium tricarn the reaction with ethanolic sodium ethoxide

The rates of elimination with sodium ethoxide in ethanol of the(2-phenyl-ethyl bromide)chromium tricarbonyl and of the(2-phenylethyl p-toluenesulphonate)chromium tricarbonyl weredetermined over a range of temperatures. The substrates gave thecomplexed styrene in 100% (Br) and 97% (OTs) yield. For comparisonthe rate of elimination of the uncomplexed 2-phenylethyl and2-( p-nitrophenyl)ethyl bromides and tosylates were measured. Complexation stronglyincreases the rate of elimination, although the effect is much lessmarked than that of a p-nitro group. The reasons for the kineticnon-equivalence between Cr(CO) 3 and p-NO 2 groups arediscussed.

The chemistry of nitro-compounds. Part III. The intramolecular nucleophilic displacement of aromatic nitro-groups by carbanions

Heating α-(N-methyl-N-o-nitrobenzoylamino)phenylacetonitrile (1a) with sodium ethoxide in ethanol affords moderate yields of 2-methyl-3-oxo-1-phenylisoindoline-1-carboxamide (3a) and benzoic acid. Similar treatment of the N-benzyl and N-phenyl o-nitrobenzamide derivatives (1b and c) yields, in addition to benzoic acid, separable mixtures of the 3-oxoisoindoline-1-carbonitriles (2b and c), the derived amides (3b and c), and the 3-phenyliso-indolin-1-ones (4b and c). Isoindolinone formation by direct intramolecular displacement of the ortho-nitro-group by the cyanobenzyl carbanion generated in the side-chain is indicated by the conversion of the amides (1a–c) in hot ethanolic sodium carbonate in high yield into the 3-oxoisoindoline-1-carbonitriles (2a–c). In addition to benzoic acid, the latter reactions respectively afford o-azidobenzoic acid (12), benzaldehyde o-carboxy-phenylhydrazone (13), and azobenzene-2-carboxylic acid (14) as by-products. The substituted benzamides (6), (7a and b), and (8a and b) are unaffected by ethanolic sodium carbonate. In contrast, the 2-nitro-5-methyl compound (6) and the 2-chloro-5-nitro-derivative (8c) are respectively converted by heating with ethanolic sodium ethoxide and ethanolic sodium carbonate into the 5-methyl- and 5-nitro-3-oxo-1,2-diphenylisoindoline-1-carbonitriles (9a and b). The mechanisms of the reactions are discussed.

The chemistry of nitro-compounds. Part II. The scope and mechanism of the base-catalysed transformations of someNN-disubstituted o-nitrobenzamides

In reactions explicable by the intermediate formation of 2-cyanoquinazolone N-oxides (2), hot ethanolic sodium ethoxide converts the N-cyanomethyl-o-nitrobenzamides (1a–c) in high yield into the N-hydroxyquinazolinediones (3a–c). In contrast, treatment of the N-benzoylmethyl-amide (6a) or the N-ethoxycarbonylmethyl-amide (6b) with ethanolic sodium ethoxide affords the indazolone (13a). The indazolones (13a and b) are formed under similar conditions from the N-α-cyanoethyl-amides (8a and b). On the other hand, hot aqueous ethanolic sodium carbonate converts the amide (8a) into a mixture of the indazolone (13a) and NN′-diphenylazobenzene-2,2′-di-carboxamide (15a); similar treatment of the amide (8b) affords the corresponding azoxybenzene derivative (16b) and benzaldehyde 2-carboxyphenylhydrazone (20). Mechanisms for the base-catalysed transformations of the amides (6a and b) and (8a and b) are discussed.

1,2-Benzisothiazoles. Part III. 3-Substituted derivatives

Ethyl (1,2-benzisothiazol-3-yl)cyanoacetate exists as a mixture of two tautomers which decomposes to (1,2-benz-isothiazol-3-yl)acetonitrile (85%) when heated in dimethyl sulphoxide. Treatment of diethyl (1,2-benzisothiazol-3-yl)malonate with ethanolic sodium ethoxide gives ethyl (1,2-benzisothiazol-3-yl)acetate, which affords 3-methyl-1,2-benzisothiazole on successive hydrolysis and decarboxylation. The methyl group in 3-methyl-1,2-benzisothiazole is resistant to oxidation. Attempted Vilsmeier–Haack formylation of 3-methyl-1,2-benzisothiazole with dimethylformamide and phosphoryl chloride gives a mixture of N2-(3-benzo[b]thienyl)-N1N1-dimethylformamidine and N2-(2-formyl-3-benzo[b]thienyl)-N1N1-dimethylformamidine. In contrast, 2-methylbenzothiazole gives (benzothiazol-2-yl)malonaldehyde or a related enamine.

Stereochemistry of a Wittig olefin synthesis in alcoholic solution

(+)-Benzylethylmethylphenylphosphonium iodide and benzaldehyde in ethanolic sodium ethoxide give (+)-ethylmethylphenylphosphine oxide: the reaction therefore proceeds with retention of configuration at phosphorus and cannot involve a vinylphosphonium salt intermediate.

Alkaline cleavage of certain phenyl- and chlorine-substituted (halomethyl)disilanes

The action of sodium ethoxide in ethanol on a number of(halomethyl)disilanes containing phenyl groups or chloride atoms on silicon has been studied. The reaction proceeds in three directions: intramolecular rearrangement involving migration of a silyl group from silicon to carbon, cleavage of the siliconsilicon bond with concomitant reduction of the halomethyl group to methyl, without evolution of hydrogen, and cleavage of the siliconsilicon bond with evolution of hydrogen. The rearrangement/cleavage proportions depend upond the nature and the position of the substituents. Possible mechanisms are discussed.

Organosilicon compounds : XLVII. Effects of α-trimethylsilyl groups on rates of reaction at carbonhalogen bonds

The compounds (Me 3Si) x CH (3− x) Cl ( x = 1–3), (Me 3Si) x CH (3− x) Br (x = 1, 3) and Me 3SiCMe 2Br have been found to react with 90% acetone or 80% ethanol at 70° at rates too small for convenient measurement. Towards aqueous acetone, the compound PhMe(Me 3Si)CBr is 110 times less reactive at 50° than PhMe 2CBr at 0°. It is concluded that relative to α-Me, α-t-Bu or α-Me 3Si groups decrease the ease of formation of carbonium ions. Second-order rate constants have been determined for the reaction of (Me 3Si) x CH (3− x) Hal compounds and of Me 3SiCMe 2Br with sodium ethoxide in ethanol at 70°, and indicate that the α-Me 3Si groups have a fairly small deactivating effect relative to the α-Me group in these reactions. Thus the compound Me 3SiCMe 2Cl is 5.6 times as reactive as (Me 3Si) 3CCl. The rates of reaction of the (Me 3Si) x CH (3− x) Cl compounds with x = 1, 2, and 3, respectively, fall in the ratios 4.8/1.2/1.0.

1,2-Benzisothiazoles. Part I. Reaction of 3-chloro-1,2-benzisothiazole with nucleophiles

3-Chloro-1,2-benzisothiazole reacts with a range of nucleophiles to give products which arise from fission of the thiazole ring. Sodium cyanide in aqueous acetone gives a mixture consisting of o-cyanophenyl thiocyanate (62%), bis-(o-cyanophenyl) disulphide (22%), and 2-acetyl-3-aminobenzo[b]thiophen (6%); copper(I) cyanide in dimethylformamide gives bis-(o-cyanophenyl) disulphide (80%); n-butyl-lithium gives o-(n-butylthio)-benzonitrile (90%); ethanolic sodium thiophenoxide gives mainly bis-(o-cyanophenyl) disulphide (50–55%), o-cyanophenyl phenyl disulphide (ca. 5%), and diphenyl disulphide (46–50%). Mechanisms involving nucleophilic attack at either sulphur or chlorine have been proposed to explain these reactions. In contrast, treatment with ethanolic sodium ethoxide affords 3-ethoxy-1,2-benzisothiazole and no ring-opened products.

Synthesis of 1-hydroxyquinoxalin-2(1H)-one 4-N-oxides

Benzofuroxan and its 5-substituted derivatives condense with benzoylacetonitrile in ethyanolic ammonia to yield the corresponding 2-cyano-3-phenylquinoxaline 1,4-di-N-oxides which are smoothly converted in warm ethanolic sodium ethoxide into 1-hydroxyquinoxalin-2-(1H)-one 4-N-oxides: the course of these reactions is discussed.

Substituent effects in the base-catalysed isomerizations of arylpropenes with ethoxide; the reaction of some aryl-substituted propenes with sodium ethoxide at 81 °C

The reactions of 3-phenylprop-1-ene and its p-methyl, m-chloro-, p-chloro-, and m- and p-bromo-derivatives, with sodium ethoxide in ethanol have been investigated at 81 °C. It was found that the effect of substituents on the rate of isomerization of these compounds to the corresponding 1-arylprop-1-enes follow the order p-Cl > m-Br ∼m-Cl > H > p-Me. The results are consistent with the view that the rearrangement occurs through the BSE1′ mechanism. The reaction of 3-(p-bromophenyl)-1-ene is complicated by the incursion of the reaction leading to nucleophilic displacement of bromine by ethoxide.

C-Alkylation of α-Amidoketones

C-Alkylations of some N-acetonyl- and N-phenacylamides were effected with alkyl halides by means of sodium ethoxide in ethanol or potassium amide in liquid ammonia. The present paper deals with its scope and structural limitation for these alkylation reactions.