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Showing papers on "Hydrazone published in 1993"


Journal ArticleDOI
TL;DR: Aldehyde N,N-dimethylhydrazones undergo facile oxidative cleavage to nitriles on reaction with magnesium monoperoxyphtalate hexahydrate (MMPP) as discussed by the authors.

71 citations


Journal ArticleDOI
TL;DR: A cluster of five drug molecules may thus be attached to a single site on a protein, giving a relatively homogeneous product in spite of the high drug conjugation ratio.

56 citations



Journal ArticleDOI
TL;DR: The enantioselective total synthesis of stenusine (1), the spreading agent of the beetle Stenus comma, is described in this article, where the silyl ether-substituted aldehyde SAMP hydrazone 2 was alkylated with (S)-1-bromo-2-methylbutane (3) yielding the hydrone 4 in high diastereomeric purity (de >95 %).
Abstract: The enantioselective total synthesis of two of the four possible stereoisomers of stenusine (1), the spreading agent of the beetle Stenus comma, is described. The silyl ether-substituted aldehyde SAMP hydrazone 2 was alkylated with (S)-1-bromo-2-methylbutane (3) yielding the hydrazone 4 in high diastereomeric purity (de >95 %). By several steps including the reduction of the hydrazone functionality and the cleavage of the N-N bond of the intermediates, 4 was converted into the BOC-protected amino alcohol 6. Subsequent cyclization of 6 afforded the (S,S) diastereomer of stenusine with 96.6 % de, >99.9 % ee, and in 11.3 % overall yield. Repetition of this synthesis using the aldehyde RAMP hydrazone (R)-2 as the starting material produced (SR)-1 with 95.0 % de, >99 % ee, and in 8.2 % overall yield. The synthetic samples of 1 were employed to investigate the stereochemistry of natural stenusine by means of GC analysis on both a chiral and an achiral, stationary phase. As a result of these studies natural stenusine was found to be a mixture of all four stereoisomers in a ratio of (S,S)/(SR)/(RR)/(R:S) = 43:40:13:4.

40 citations



Journal ArticleDOI
TL;DR: The rhodium(II) carboxylate catalyzed decomposition of several α-diazo esters and amides has been studied in this article, where a series of 5-keto-1diazos acetates were prepared by acylation of α-hydroxy ketones using the (p-toluenesulfonyl)hydrazone of glyoxylic acid chloride.
Abstract: The rhodium(II) carboxylate catalyzed decomposition of several α-diazo esters and amides has been studied. A series of 5-keto-1-diazo acetates were prepared by acylation of α-hydroxy ketones using the (p-toluenesulfonyl)hydrazone of glyoxylic acid chloride. Treatment of these compounds with Rh(II) acetate afforded products derived from carbenoid insertion into solvent. When the hydrogen atom of the diazo carbon was replaced with an electron-withdrawing substituent, smooth cyclization occurred to produce a carbonyl ylide dipole which was subsequently trapped with different dipolarophiles. A series of N-alkyl-2-diazo-π-oxobutylamides, when treated with a catalytic quantity of rhodium(II) acetate, gave furo[3,4-c] furans in good yield. The reaction proceeds via addition of a rhodium stabilized carbenoid onto the acetylenic π-bond to give a vinyl carbenoid which subsequently cyclizes onto the neighboring carbonyl group to produce the furan ring. N-Alkynyl-substituted 2-diazoacetamides were also found to cyclize onto the tethered alkyne unit. The resulting rhodium carbenoid can undergo intramolecular and bimolecular cyclopropanation depending on both electronic and conformational factors. Rotamer population of the starting diazoamide was also found to influence product distribution

39 citations


Journal ArticleDOI
01 May 1993-Synlett
TL;DR: In this paper, a general and selective procedure for the diastereoselective additions of organocerium reagents to chiral α,α-dialkoxy hydrazones has been developed.
Abstract: A general and selective procedure for the diastereoselective additions of organocerium reagents to chiral α,α-dialkoxy hydrazones has been developed. The best reagent combination involved a 6:1 composition of RMet to CeCl3. Excellent yields and high selectivities were obtained after trapping as the iso-butyl carbamates. Lithiumammonia cleavage of the N-N bond followed by hydrolysis with TMSI afforded the protected α-amino aldehydes.

35 citations


Journal ArticleDOI
TL;DR: In this article, the Lewis-acid-promoted reaction of allyltrimethylsilane with enones was shown to afford the 3-allyl ketone derivatives (Sakurai products) along with the trimethylsilylcyclopentanes ([3+2] cycloaddition products).

29 citations


Journal ArticleDOI
TL;DR: Intermediates 4 and 5 have been coupled via a Shapiro reaction to afford compound 6 which has been further elaborated to the ABCtaxcid systems 11and 12via a McMurry pinacol cyclization to 11followed by oxidation to 12.
Abstract: Intermediates 4 and 5have been coupled via a Shapiro reaction to afford compound 6 which has been further elaborated to the ABCtaxcid systems 11and 12via a McMurry pinacol cyclization to 11followed by oxidation to12.

28 citations


Journal ArticleDOI
TL;DR: In this article, a series of complexes with the tridentate dibasic Schiff base ligand o-vanillin isonicotinoyl hydrazone (o-VINH) were prepared and characterized by i.a.p. and electronic spectral studies, magnetic susceptibility measurements and t.m.
Abstract: A new series of complexes with the tridentate dibasic Schiff base ligand o-vanillin isonicotinoyl hydrazone (o-VINH) were prepared and characterized by i.r., 1H n.m.r. and electronic spectral studies, magnetic susceptibility measurements and t.g.a. The disappearance of low field signals due to OH, NH protons at 10.23 and 9.31 p.p.m. and downfield shift of the −CH=N proton signal at 8.17 p.p.m. in the n.m.r. spectrum confirms the involvement of these groups in coordination. Both t.g.a. and i.r. spectral data show evidence for one molecule of coordinated H2O. These results taken in conjunction with electronic spectral data allow assignation of tetrahedral geometry for manganese(II), nickel(II) and palladium(II) complexes but a square planar configuration to cobalt(II), copper(II) amd zinc(II) complexes.

28 citations


Journal ArticleDOI
TL;DR: In this article, N-Toluenesulfonyl- and N-(anilinocarbonyl)pyrazolo-3-sulfolenes have been prepared from the protected oxotetrahydrothiophene carbaldehyde via a sequence of hydrazone formation, ketal hydrolysis, cyclization, dehydration, and oxidation reactions.
Abstract: N-Toluenesulfonyl- and N-(anilinocarbonyl)pyrazolo-3-sulfolenes have been prepared from the protected oxotetrahydrothiophenecarbaldehyde (7) via a sequence of hydrazone formation, ketal hydrolysis, cyclization, dehydration, and oxidation reactions. These N-substituents migrate between the two nitrogen atoms of the pyrazole ring at different stages. Extrusion of SO 2 from N-anilinocarbonylpyrazolo-3-sulfolenes was achieved at 180-200°C and the transient intermediate, the pyrazolo-o-quniodimethane, could be trapped with dienophiles

Journal ArticleDOI
TL;DR: In this paper, various α-substituted (Y) acetone hydrazones were subjected to the Hurd-Mori reaction to give the 4-methyl-5-Y-substantituted 1,2,3-thiadiazoles and/or 4-Y CH 2 derivatives.
Abstract: Various α-substituted (Y) acetone hydrazones were subjected to the Hurd-Mori reaction to give the 4-methyl-5-Y-substituted 1,2,3-thiadiazoles and/or 4-Y-CH 2 derivatives. The ratio of the two products changed drastically depending on the kind of the substituent Y and was parallel to the relative rate of enolization of the two α-carbons in the parent ketones

Journal ArticleDOI
TL;DR: In this paper, a simple and efficient enantioselective synthesis of 2-substituted 4-oxosulfones in 40 -71% overall chemical yield and enantiomeric excesses of 86-97% is described.

Journal ArticleDOI
TL;DR: In this article, a series of dihydrazone and substituted dihydron derivatives of biacetyl and of hydrazone were found to give PF6-2Cl2 complexes, and the structures of all complexes were determined using IR, UV/VIS, NMR and microanalysis.
Abstract: A series of dihydrazone and substituted dihydrazone derivatives of biacetyl and of hydrazone and phenylhydrazone derivatives of 2-acetylpyridine bind to [Ru(bipy)2Cl2] to give [Ru(bipy)2(L–L)][PF6]2 complexes {bipy = 2,2′-bipyridine; L–L = biacetyl di(phenylhydrazone)1a, biacetyl di[methyl(phenyl)hydrazone]1b, biacetyl di(o-tolylhydrazone)1c, biacetyl di(dimethylhydrazone)1d, biacetyl dihydrazone 1e, biacetyl di(benzaldehyde azine)1f, 2-acetylpyridine phenylhydrazone 1g, or 2-acetylpyridine hydrazone 1h}. The structures of all complexes have been determined using IR, UV/VIS, NMR and microanalysis. The proton NMR spectra of 1a–1c show an unusual dependence on probe temperature with broadened aromatic resonances, sharpening at both high and low temperature in the case of 1b and 1c. No emission was observed for complexes with two hydrazone moieties, whereas it was observed for 1g and 1h with one hydrazone. The molecular structure of 1a has been determined and shows a hydrazone phenyl group lying over each of the bipyridyl rings: space group C2/c, a= 25.895(3), b= 10.505(1), c= 17.431(2)A, β= 106.03(2)° and Z= 4.

Journal ArticleDOI
TL;DR: In this article, the potential energy surfaces corresponding to the Beckmann rearrangement of protonated formaldehyde oxime and formaldehyde hydrazone in the gas phase have been explored using ab initio molecular orbital calculations.
Abstract: The potential energy surfaces corresponding to the Beckmann rearrangement of protonated formaldehyde oxime and formaldehyde hydrazone in the gas phase have been explored using ab initio molecular orbital calculations. Geometries of stationary points were optimized at the HF and MP2/6–31G(d,p) level while relative energies were estimated at the MP4SDTQ/6–311++ G(d,p) level and corrected for zero-point energies. Both rearrangements are calculated to be concerted with a single transition structure, connecting the protonated species and the product complex. In the transition structure, the 1,2-hydrogen shift from C to N is accompanied by a lengthening of the N–O (in oxime) or N–N (in hydrazone) distance, and the migrating hydrogen is in trans relative to the leaving group across the CN bond. The transition structure in the hydrazone case is much closer to the final products than that in the oxime. This is also manifested by the energy barriers that amount to 44 and 189 kJ mol–1 for oxime and hydrazone, respectively. These results suggest that the Beckmann rearrangement of oxonium ion is a facile process, while that of hydrazonium ion is reachable under thermal conditions. The experimentally observed loss of HCN from hydrazonium ion can be better rationalized in terms of a Beckmann rearrangement than a 1,2-cis-elimination as recently proposed. The proton affinities at different sites in oxime and hydrazone are also evaluated.


Journal ArticleDOI
TL;DR: In this article, the synthesis of an extended series of mononuclear and binuclear iron complexes based on oxime-hydrazone ligands was reported, and the cobalt clathrochelate complexes were shown to be stable in both the +2 and the +3 oxidation states.
Abstract: The synthesis of an extended series of mononuclear and binuclear iron complexes based on oxime-hydrazone ligands is reported. In addition, the syntheses of the first examples of cobalt clathrochelate complexes utilizing oxime- hydrazone ligands are presented. The structures of the new complexes are established through elemental analysis and NMR spectral characterization. Cyclic voltammotric and electrolytic studies illustrate that the oxidation of the iron to the 3+ state does not produce a stable complex; however, the cobalt complexes are shown to be stable in both the +2 and the +3 oxidation states

Journal ArticleDOI
TL;DR: In this paper, solvent extraction behaviors of these compounds for alkali metal ions were evaluated spectrophotometrically and the composition of the extracted species and the K+-selectivity depended on the polarity of the extraction solvent used.
Abstract: Four types of benzo-15-crown-5 and benzo-18-crown-6 derivatives bearing a substituted hydrazone moiety as a proton-dissociable chromogenic group were synthesized and the solvent extraction behaviors of these compounds for alkali metal ions were evaluated spectrophotometrically. Benzo-15-crown-5 and -18-crown-6 hydrazones with 2,4-dinitro-6-(trifluoromethyl)phenyl or 2,6-dinitro-4-(trifluoromethyl)phenyl groups extracted alkali metal ions predominantly as 2 : 1 and 1 : 1 (crown ether : metal ion) complexes, respectively, from an aqueous alkaline solution into 1,2-dichloroethane and these ligands exhibited high K+-selectivity. The composition of the extracted species and the K+-selectivity depended on the polarity of the extraction solvent used. In particular, 2 : 2 complexes of several alkali metal ions with benzo-15-crown-5 and -18-crown-6 hydrazones bearing a 2,4-dinitro-6-(trifluoromethyl)phenyl group were readily extracted from an aqueous solution into chloroform.

Journal ArticleDOI
TL;DR: A new hydrazone derivative, di-2-pyridyl ketone [phenyl(semicarbazono)acetyl]hydrazone (H2L), has been prepared and examined as a chelating agent towards metal ions.
Abstract: A new hydrazone derivative, di-2-pyridyl ketone [phenyl(semicarbazono)acetyl]hydrazone (H2L), has been prepared and examined as a chelating agent towards metal ions. The molecular structure of the copper complex [Cu2LCl2]·H2O consists of a pair of structurally distinct metal centres with different environments bound to the heptadentate hydrazonic ligand and held together by a –N–N– bridge.


Journal ArticleDOI
TL;DR: The binding properties of p-(phenylazo)calix[n]arenes (n = 6 and n = 4) for metal ions have been studied in this paper.
Abstract: The binding properties of p-(phenylazo)calix[n]arenes (n = 6 and n = 4) for metal ions have been studied. The calixarenes show a highly selective binding ability toward Ag+, Hg+, and Hg2+. This property can be explained in terms of a metal ion-induced azo/hydrazone tautomerism. The Ag+ ion forms complexes with the azocalixarenes by binding with their hydrazone tautomers.

Journal ArticleDOI
TL;DR: In this article, a trialkylsilyl trifluoromethanesulfonate mediated ring opening of tetrahydrofuran with lithiated SAMP-/RAMP- or SADP-hydrazones was presented.
Abstract: α-Siloxybutylated aldehydes and ketones 4 are synthesized in good overall yields and high enantiomeric purities (ee ≥95%; 81%) by trialkylsilyl trifluoromethanesulfonate mediated ring opening of tetrahydrofuran with lithiated SAMP-/RAMP- or SADP-hydrazones

Journal ArticleDOI
TL;DR: In this paper, it was shown that α-Ketoacids and ketones can be regenerated in high yield from their phenylhydrazones via hydroxy azo compounds upon oxidation with hupervalent iodine reagents.


Journal ArticleDOI
TL;DR: In this paper, the acyclic and cyclic monoazatetrathioether derivatives incorporating a substituted hydrazone group were synthesized and showed high Ag+ ion selectivity in the extraction with 1,2-dichloroethane.
Abstract: Novel acyclic and cyclic monoazapolythioether derivatives incorporating a substituted hydrazone group were synthesized. The acyclic and the cyclic monoazatetrathioether derivatives exhibited high Ag+ ion selectivity in the extraction with 1,2-dichloroethane. The monoazatetrathioether derivatives gave hypsochromic and bathochromic shifts in the visible absorption spectra when extracted Ag+ ion from the aqueous phase of varying acidities into the organic phase.

Journal ArticleDOI
TL;DR: In this article, an efficient and flexible synthesis of 1,2-trans-substituted cycloalkanecarboxylates and sulfones of high diastereo and enantiomeric purity is described.
Abstract: Diastereo- and Enantioselective Synthesis of 1,2-trans-substituted Cycloalkanecarboxylates and Sulfones by Michael-Initiated Cyclisation via SAMP / RAMP Hydrazones[1,2] An efficient and flexible synthesis of 1,2-trans-substituted cycloalkanecarboxylates and sulfones of high diastereo- and enantiomeric purity is described. The key step of the procedure is a Michael-initiated ring closure (MIRC) reaction employing the SAMP/RAMP hydrazone method. Depending on the chain length of the ω-bromo(iodo)enoates 2, 3 and the type of ketone SAMP-hydrazone 1, 3-, 5-, 6- and 7-membered cycloalkane-carboxylates 4–7 or cyclopentanesulfones 24 bearing two or three stereogenic centers are formed with very high asymmetric induction. In the same manner, MIRC reactions with ω-(ethoxycarbonyl)enoate 26 give rise to 3-substituted cyclopentanone-2-carboxylates 27, but with lower overall chemical yields. The relative and absolute configurations are based on X-ray structure analyses, spectroscopic and mechanistic investigations.

Journal ArticleDOI
TL;DR: This article showed that sterically hindered hydrazones with tellurium dichloride in the presence of triethylamine in benzene afforded Δ3-1,3,4-telluradiazolines, a novel heterocycle, probably via 1,3-dipolar cycloaddition of telluroketones with diazo compounds, both generated in situ.
Abstract: Reaction of sterically hindered hydrazones with tellurium dichloride in the presence of triethylamine in benzene afforded Δ3-1,3,4-telluradiazolines, a novel heterocycle, probably via 1,3-dipolar cycloaddition of telluroketones with diazo compounds, both generated in situ.


Journal ArticleDOI
TL;DR: In this paper, the reactions of 2,2,4, 4,4-tetramethyl-1,5-diphenyl-1.5-pentanedione monohydrazone with S 2Cl2 and Se2Cl2 gave 2.2.
Abstract: The reactions of 2,2,4,4-tetramethyl-1,5-diphenyl-1,5-pentanedione monohydrazone with S2Cl2 and Se2Cl2 gave 2,2,4,4-tetramethyl-1,5-diphenyl-8-oxa-6,7-dithiabicyclo[3.2.1]octane (9) and 2,2,4,4-tet...

Journal ArticleDOI
Zhang Hongyun1, Li Feng1, Chen Peikun1, Che Deji1, Chen Dongli1, Zhang Hongquan1 
TL;DR: In this article, the lead-II coordination compounds of acetylferrocenylnaphthoylhydrazone and 1,1′-diacetylferrrocene with 3-hydroxyl-2-naphTHYlhydrazine have been obtained.