Showing papers in "Journal of Chemical Research-s in 1997"
TL;DR: In this article, values in DMSO are reported for ammonium ions derived from amines which have been widely used as nucleophiles in nucleophilic substitution reactions; values are also given for four different types of amines used as indicators.
Abstract: pK a
Values in DMSO are
reported for ammonium ions derived from amines which have
previously been widely used as nucleophiles in nucleophilic
aromatic substitution reactions; values are also given for four
polynitrodiphenylamines used as indicators
98 citations
TL;DR: Substituted coumarins are synthesised from methylーテacetoacetate and substituted phenols using microwaves in good yields as mentioned in this paper. But they are not suitable for indoor use.
Abstract: Substituted coumarins are synthesised from methyl
acetoacetate and substituted phenols using microwaves in
excellent yields.
60 citations
TL;DR: An easy preparation of 1,1-diacetates from deadehydes with montmorillonite clays as catalysts has been successfully carried out in this paper.
Abstract: An easy preparation of 1,1-diacetates from
aldehydes with montmorillonite clays as catalysts has been
carried out in excellent yield.
52 citations
Abstract: Condensation of indoles with carbonyl compounds in the presence of montmorillonite clay produces bis(indol-3-yl)methanes in good yield; an extension of this procedure, involving nucleophilic ring opening of oxiranes, produces 1,2-bis(indol-3-yl)ethanes.
47 citations
TL;DR: Flash vacuum pyrolysis of 3-(2-hydroxyaryl)propenoic esters gives coumarins (and otherfused α-pyrones) in high yield as mentioned in this paper.
Abstract: Flash vacuum pyrolysis of3-(2-hydroxyaryl)propenoic esters gives coumarins (and otherfused α-pyrones) in high yield.
46 citations
TL;DR: Iodine catalyses the acetylation of amines, phenols and alcohols, including tertiary ones, including secondary ones, with acetic anhydride in excellent yield.
Abstract: Iodine catalyses the acetylation of amines, phenols
and alcohols, including tertiary ones, with acetic anhydride in
excellent yield.
38 citations
TL;DR: In this article, biologically active fusedquinazolines have been synthesized via treatment of N-acyl/ aroylaminoquinazolin-4(3H)-one with various nucleophilic reagents; some of the products showed moderate antibacterial activity.
Abstract: We report that biologically active fused
quinazolines have been synthesized via treatment of
3-(N-acyl/ aroylamino)quinazolin-4(3H)-ones (2)
with various nucleophilic reagents; some of the products showed
moderate antibacterial activity.
34 citations
TL;DR: In this paper, a rapid and efficient method for the synthesis of============alkyl======4-aryl,1,4,5,6,7,8-hexahydro,2, 7,7-trimethyl-5-oxoquinoline-3-car":""},{"¯¯¯¯¯¯boxylates by the condensation of======5,5-dimethylcyclohexane-1,3-dione and aromatic aldehydes with======methyl 3-aminocrotonate or ethyl acetoacetate in the presence of
Abstract: A rapid and efficient method for the synthesis of
alkyl
4-aryl-1,4,5,6,7,8-hexahydro-2,7,7-trimethyl-5-oxoquinoline-3-car
boxylates by the condensation of
5,5-dimethylcyclohexane-1,3-dione and aromatic aldehydes with
methyl 3-aminocrotonate or ethyl acetoacetate in the presence of
ammonium acetate and of pyrimido[4,5-b]quinolines by the
condensation of N-methylaniline with an aromatic
aldehyde and 1,3-diaryl-2-thiobarbituric acid using microwave-
and ultrasound-induced methods is reported.
30 citations
TL;DR: A convenient synthesis of the important metabolite 7-hydroxycoumarin glucuronide 3 is presented, including a first report of the β-imidate 11β, together with new preparations of the iodosugar 6 and α-imidates 11α.
Abstract: A convenient synthesis of the important metabolite 7-hydroxycoumarin glucuronide 3 is presented, including a first report of the β-imidate 11β, together with new preparations of the iodosugar 6 and α-imidate 11α: stability data on 11α and 11β are also given, and the importance of carefully controlled hydrolysis in the last step of the preparation of 3 is emphasised.
29 citations
TL;DR: In this article, a highly selective reagent for the oxidation of allylic methyl groups to β-unsaturated aldehydes under MICROWave irradiation was found. But this reagent is not suitable for methyl groups with high acidity.
Abstract: SeO 2
/Bu
t
OOH adsorbed on
SiO
2
is found to be a highly selective reagent for the
oxidation of allylic methyl groups to
trans-α,β-unsaturated aldehydes under
microwave irradiation.
29 citations
TL;DR: In this paper, anArenes are oxidized into ketones within 10-30min using microwave activation in a dry media, instead of several days under classical conditions, and they are impregnated on alumina under microwave activation.
Abstract: Arenes are oxidized into ketones within 10–30min using KMnO
4
impregnated on alumina under microwaveactivation in dry media, instead of several days under classicalconditions.
TL;DR: In this paper, 15 new 3-substituted 7-hydroxycoumarins emitting in the blue-green region of the visible spectrum are synthesized, some of which show laser activity.
Abstract: With a view to extend the tunability range and
maximum output of the coumarin series of dyes, 15 new
3-substituted 7-hydroxycoumarins emitting in the blue-green
region of the visible spectrum are synthesized, some of which
show laser activity.
TL;DR: Several newnaphtho[2′,1′:5,6]pyrano[2,3d]pyrimidines have been synthesized via¯¯¯¯¯¯ hydrazinolysis of a2-ethoxymethylideneaminonaphTHo[1,2-b======€€ 1.
Abstract: Several newnaphtho[2′,1′:5,6]pyrano[2,3-d
]pyrimidineshave been synthesized via
hydrazinolysis of a2-ethoxymethylideneaminonaphtho[1,2-b
]pyran;polysubstitutedpyrano[3,2-e
][1,2,4]triazolo[1,5-c
]pyrimidineshave also been prepared.
TL;DR: Fe III –EDTA in aqueous methanol offers a simple environmentally acceptable synthetic tool foroxidizing thiols to the corresponding disulfides by molecularoxygen in excellent yields, under mild conditions and devoid of side reactions.
Abstract: Fe III
–EDTA in aqueous methanoloffers a simple environmentally acceptable synthetic tool foroxidizing thiols to the corresponding disulfides by molecularoxygen in excellent yields, under mild conditions and devoid ofside reactions.
TL;DR: Isocyanides undergo formal cycloaddition with 3-(1-hydroxyethylidene)pentane-2,4-dione to afford five-memberediminolactone derivatives in high yields.
Abstract: Isocyanides undergo formal [1+4] cycloaddition with3-(1-hydroxyethylidene)pentane-2,4-dione to afford five-memberediminolactone derivatives in high yields.
TL;DR: In this paper, the intramolecularity of the thermal rearrangement of 1-aryl-5-allyloxy-1H-tetrazoles has been investigated through cross-over studies.
Abstract: The intramolecularity of the thermal rearrangement
of 1-aryl-5-allyloxy-1H-tetrazoles 1 to
1-aryl-4-allyl-1,4-dihydrotetrazol-5-ones 2 has been investigated
through cross-over studies: the results support the hypothesis
for a concerted sigmatropic rearrangement occurring through a
highly polar transition state, in which a partially positively
charged allyl group migrates from oxygen to nitrogen, without
leaving the solvent cage.
TL;DR: In this article, NMR chemical shifts of the acetate and pyridine ligands α-position were analyzed in the presence of inductive, paramagneticanisotropy and ring current effects.
Abstract: The 1
H and 13
C NMR chemicalshifts of the acetate and pyridine ligands α-position) in aseries of[Ru
3
O(CH
3
CO
2
)
6
L
3
]
+
clusters are linearly correlated with thepK
a
(L), but exhibit variable trends at thevarious positions as a consequence of the inductive, paramagneticanisotropy and ring current effectsand the ligand interactionsthrough the Ru
3
O core.
TL;DR: The oxidation potential of L-ascorbic acid at a glassy carbon electrode shifts from 200 mV (vs. SCE) in phosphate buffer at pH 6.8 to 10 mV in the presence of cetyltrimethylammonium bromide micelles, and to 460 mV in the Presence of sodium dodecyl sulfate (SDS) micells.
Abstract: The oxidation potential of L-ascorbic
acid at a glassy carbon electrode shifts from 200 mV (vs.
SCE) in phosphate buffer at pH 6.8 to 10 mV in the presence
of cetyltrimethylammonium bromide (CTAB) micelles, and to 460 mV
in the presence of sodium dodecyl sulfate (SDS) micelles.
TL;DR: Heteroaromatic amines react with 1-substituted======3-dimethylaminopropanones, with enaminones and with======cinnamonitriles to yield azolopyrimidines or azopyridines.
Abstract: Heteroaromatic amines react with 1-substituted
3-dimethylaminopropanones, with enaminones and with
cinnamonitriles to yield azolopyrimidines or azolopyridines.
Journal Article•
TL;DR: In this paper, the rate of disappearance of cerium(IV) in the reaction has been found to be zero order with respect to cerium (IV) concentration in the presence of ruthenium(III) in aqueous sulfuric acid media.
Abstract: The kinetics of oxidation of formic acid by cerium(IV) in the presence of ruthenium(III)(ca. 10–6 mol dm–3) in aqueous sulfuric acid media has been followed at different temperatures (30–50 °C). The rate of disappearance of cerium(IV) in the reaction has been found to be zero order with respect to cerium(IV) concentration. At a fixed [H+], under the conditions, [HCO2H]T[CeIV]T[Ru]T the observed zero-order rate constant (k0) conforms to: –d[CeIV]t/dt=k0=[Ru]T[HCO2H]T{kb+kc[HCO2H]T} where [Ru]T and [HCO2H]T represent the total concentration of ruthenium(III) and formic acid respectively. At 40 °C, [H2SO4]= 1.0 mol dm–3 and I= 2.75 mol dm–3 the values of 102kb and 102kc are 6.0 ± 0.1 dm3 mol–1 s–1 and 5.4 ± 0.1 dm6 mol–2 s–1 respectively. Both kb and kc are found to have an inverse hydrogen-ion dependence. Out of the different possible mono- and bis-complexes, RuIII(HCO2–) and RuIII(HCO2–)(HCO2H) have been found to be kinetically active in the slow oxidative steps (through an inner-sphere mechanism) leading to RuIIIH (through hydride transfer from the C–H bond of metal-bound formate) and CO2 followed by the rapid oxidation of RuIIIH to RuIII by cerium(IV). The activation parameters are ΔH‡= 46 ± 3 kJ mol–1, ΔS‡=–125 ± 5 J K–1 mol–1(for the kb path) and ΔH‡= 47 ± 3 kJ mol–1, ΔS‡=–120 ± 5 J K–1 mol–1(for the kc path).
TL;DR: In this paper, Dialkyl 1,2-dihydroquinoline-2,3-dicarboxylates are formed in a one-pot reaction from amide derivatives of======2-aminobenzaldehyde, dialkyl acetylenedicarboxesylates and======triphenylphosphine in CH============ 2====== 1.
Abstract: Dialkyl 1,2-dihydroquinoline-2,3-dicarboxylates are
formed in a one-pot reaction from amide derivatives of
2-aminobenzaldehyde, dialkyl acetylenedicarboxylates and
triphenylphosphine in CH
2
Cl
2
in high
yields.
TL;DR: In this paper, a novel synthesis of condensed methylsulfanylazoles via the treatment of amino-and======[bis(methyl sulfanyl)methylidene]malononitrile with amino- and======676oxoxo-azoles is reported and the synthetic potential of the method is demonstrated.
Abstract: A novel synthesis of condensed methylsulfanylazoles
via the treatment of
[bis(methylsulfanyl)methylidene]malononitrile with amino- and
oxo-azoles is reported and the synthetic potential of the method
demonstrated.
TL;DR: In this article, the synthesis of 2-substituted 4H======-3,1-benzoxazin-4-ones by the condensation ofanthranilic acid and orthoesters under classical heating andmicrowave irradiation is described.
Abstract: The synthesis of 2-substituted4H
-3,1-benzoxazin-4-ones by the condensation ofanthranilic acid and orthoesters under classical heating andmicrowave irradiation is described.
TL;DR: In this article, the preparation and structural characterization of 4,4′-(1,4-phenylene)di-pyridine and -pyrimidine derivatives are described.
Abstract: The preparation and structural characterization of4,4′-(1,4-phenylene)di-pyridine and -pyrimidine derivativesare described.
TL;DR: In this paper, the side chain has been synthesized by sequential Arnold-Vilsmeier and Wittig reactions, subsequent biochemical studies showing the formation of either a dimeric structure or the occurrence of E/Z-isomerization.
Abstract: C-16-substituted steroids having an unsaturation in
the side chain have been synthesized by sequential
Arnold–Vilsmeier and Wittig reactions, subsequent
photochemical studies showing the formation of either a dimeric
structure or the occurrence of E/Z-isomerization; for
one example, treatment with H
2
over Pd–C led to
full reduction of the side-chain and ring D.
TL;DR: In this article, aldehydes and ketones are catalysed by montmorillonite K-10 in refluxing benzene or toluene in good yields.
Abstract: Acetalization of aldehydes and ketones is catalysed
by montmorillonite K-10 in refluxing benzene or toluene in
excellent yields.
TL;DR: In this paper, α-methylene sulfones react with dimethyl carbonate to yield the corresponding mono-C-methyl derivatives in a selectivity >99, at conversions of 76-99% (isolated yields: 97-92%).
Abstract: At 180–210 °C, α-methylene sulfones (both benzyl aryl and alkyl aryl sulfones, RCH
2
SO
2
AR: R = Ph, p-ClC
6
H
4
, Ar = Ph, p-ClC
6
H
4
, p-MeC
6
H
4
, and R = Me, Ar = Ph, p-ClC
6
H
4
, p-MeC
6
H
4
) react with dimethyl carbonate to yield the corresponding mono-C-methyl derivatives [RCH(CH
3
)SO
2
Ar] in a selectivity >99%, at conversions of 76–99% (isolated yields: 97–92%).
TL;DR: In this paper, the synthesis of novel derivatives of pyrazolo[1,5a]-s-triazine, pyrazol[3,4d][1,3]thiazine and pyrimidine, starting from 4-substituted 5-aminopyrazole-1-carbothioamides, are reported.
Abstract: The syntheses of novel derivatives of pyrazolo[1,5-a]-s-triazine, pyrazolo[3,4-d][1,3]thiazine and pyrazolo[3,4-d]pyrimidine, starting from 4-substituted 5-aminopyrazole-1-carbothioamides, are reported.
TL;DR: In this article, a self-complementary molecule organized in tapes using aqua ligands and carboxylate groups as hydrogen bond donors was synthesized and the structure confirmed by X-ray crystallography.
Abstract: [Ni 3
(trim)
2
(H
2
O)
14
]·4H
2
O (trim=trimesate trianion), a
self-complementary molecule organised in tapes using aqua ligands
as hydrogen bond donors and carboxylate groups as hydrogen bond
acceptors, is synthesised and the structure confirmed by X-ray
crystallography.