bluuebunny/crossref_metadata_2025 huggingface dataset:
The stereoselective synthesis of substituted 1‐hydroxyazetidines
Authors: van Elburg Paulus A. , Reinhoudt David N. , Harkema Sybolt
Published: September 2010

The four‐membered cyclic nitrones (2,3‐dihydroazete l‐oxides) 1a‐d and 2a‐c react with a variety of nucleophiles by stereoselective addition to the nitrone moiety. Reaction of the nitrones 1 and 2 with alkyl‐, allyl‐, benzyl‐, and arylmagnesium halides yields the l‐hydroxyazetidines 3, 4, 5, and 6, with the nucleophile adding from the less hindered side of the molecule. The keto nitrone 1b reacts with potassium cyanide to give the l‐hydroxyazetidine 4f. Reduction of nitrone 1b to give the l‐hydroxyazetidines 7 and 8 is achieved by reaction with lithium aluminum hydride at 0°C and at room temperature, respectively. In contrast, nitrone 1d reacts with lithium aluminum hydride only at 45°C to give the l‐hydroxyazetidine 11. The differences in the reactivity of the nitrones 1 and 2 towards nucleophilic reagents are explained in terms of steric hindrance in the addition step. Oxidation of the l‐hydroxyazetidine 3b with lead(IV) oxide affords the 2,3‐dihydroazete l‐oxide 15. Reduction of nitrone 15 with sodium borohydride affords the 1‐hydroxyazetidine 16, the epimer of compound 3b. Reaction of l‐hydroxyazetidine 3d with PbO2 yields the dimeric structure 17. Nitrone 1a reacts with the sodium salt of nitromethane to yield the l‐hydroxyazetidine 12. Keto nitrone 1b reacts with 4‐nitrobenzaldehyde in the presence of a catalytic amount of potassium hydroxide to give the 4‐benzylidene‐2,3‐dihydroazete l‐oxide 13. Upon prolonged reaction, nitrone 13 isomerizes to oxime 14, probably by an electrocyclic ring opening of an intermediate l‐hydroxy‐1,2‐dihydroazete.
Synthesis of three isotopomers of L‐tryptophan via a combination of organic synthesis and biotechnology
Authors: van den Berg E. M. M. , Baldew A. U. , de Goede A. T. J. W. , Raap J. , Lugtenburg J.
Published: September 2010

In this paper, we report the preparation of three isotopomers of L‐tryptophan on a gram scale, specifically labelled with 99% 15N (position 1) and 99% 13C (position 2) in the indole ring; for position 3, the incorporation was 90% 13C. The isotopically enriched indoles were synthesized from H15NO3, K13CN and 13CH3CN and then converted, with L‐serine, into the correspondingly labelled L‐tryptophans using genetic manipulated E. coli bacteria, which contain high amounts of the enzyme tryptophan synthetase. The 13C‐13C, 13C‐1H, 13C‐15N and 15N‐1H coupling constants of the indoles and the tryptophans were determined from the 1H NMR and 13C NMR spectra.
Synthesis and conformational analysis of phosphorus‐derivatized no‐base analogues of 3′, 5′ ‐cyclic nucleotides
Authors: Hermans Rob J. M. , Buck Henk M.
Published: September 2010

A number of epimeric pairs of 3‐X‐3‐oxo‐trans‐2, 4, 7‐trioxa‐3‐phosphabicyclo[4.3.0]‐nonanes [5, X  OCH3; X  OPh; 7, X  Cl; 8, X  N(CH3)2; 9, X  S−; 10, X  O−] have been prepared as no‐base analogues of 3′,5′‐cyclic nucleotides. 1H NMR analysis shows the phosphate ring of the cis diastereomers (relationship of singly bonded substituent on phosphorus and proton H1) 5a–7a, 9a and 10 and the trans diastereomers 8b and 9b to be in the chair conformation 15. The phosphate rings of the epimers 5b–7b and 8a exist as an equilibrium between chair conformation 15 and twist conformation 16. The mole fraction of twist depends on the nature of the singly bonded substituent and varies from about 0.3 for 5b to 0.8 for 7b. The close similarity in coupling constants of the tetrahydrofuran ring of the phosphates 5–10 indicates that the population of a twist conformer has little effect on the conformation of this ring, which is close to 4E‐4T3. The results obtained for 5–10 are compared with those of conformational studies on corresponding phosphates derived from thymidine and cyclopentane.
Theoretical and molecular modelling studies on organic transition metal complexes. III. Calculation of the conformational energies of transition‐metal dichloro‐bis(pyridine) complexes using an extended CNDO/2 method
Authors: Morley John O.
Published: September 2010

Calculations are reported on the conformational energies of the dichloro‐bis(pyridine) complexes of zinc, copper, nickel and cobalt. Results based on experimental geometries show that the tetrahedral conformer of the zinc complex is favoured over the corresponding square‐planar structure in line with experimental data, but the latter is preferred for the copper complex though the energy differences between both conformers is small. Square‐planar conformations are predicted for the nickel and cobalt complexes.
Sulfonation and sulfation in the reactions of the chloro‐ and dichlorophenols, 3‐fluorophenol and (2,3‐, 2,4‐ and 3,4‐dichlorophenoxy)acetic acid with concentrated aqueous sulfuric acid and sulfur trioxide
Authors: de Wit Peter , Cerfontain Hans
Published: September 2010

The chloro‐ and dichlorophenols have been sulfonated with sulfuric acid and with SO3 in aprotic solvents. In the sulfonations with concentrated aqueous sulfuric acid, the sulfonic acid isomer distribution is determined mainly by the ortho‐ and para‐directing and activating effect of the hydroxy substituent; this is also the determining factor in the aprotic sulfonations using up to 1.0 equiv of SO3. Upon using larger amounts of SO3, the sulfonation isomer distribution is increasingly determined by additional sulfonation of the corresponding phenyl hydrogen sulfate, of which the ‐OSO3H substituent is deactivating and mainly para‐ (and further ortho‐) directing.

The sulfuric acid sulfonation of (2,3‐, 2,4‐ and 3,4‐dichlorophenoxy)acetic acid leads to the exclusive formation of the 4‐, 6‐ and 6‐sulfonic acid, respectively.
A spectroscopic study of the interaction between lanthanide ions and their surroundings in lanthanide magnesium nitrate hydrate (Ln2Mg3(NO3)12· 24H2O)
Authors: Blasse G. , Dirksen G. J. , van Vliet J. P. M.
Published: September 2010

The absorption and emission spectra of the mixed nitrates Ln2Mg3(NO3)12·24H2O (Ln = La, Ce, Eu, Gd) are reported. The interaction between the 4f electrons of the Ln3+ ion and the nitrate group is unexpectedly strong. This is apparent from a strong additional absorption in the case of Ce3+ and strong cooperative vibronic emission and absorption lines in the case of Eu3+.
Preparation and reactions of a disilyne synthon, 7,7′‐bis(7‐methyl‐1,4,5,6‐tetraphenyl‐7‐sila‐2,3‐benzo‐norbornadiene)
Authors: Sekiguchi Akira , Zigler Steven S. , Haller Kenneth J. , West Robert
Published: September 2010

The title compound (2) was prepared by condensing a bis(silole) 1 with benzyne. Thermolysis of 2 in the presence of anthracene, 9,10‐dimethylanthracene (DMA), 2,3‐dimethylbutadiene, and two acetylenes is described in detail. X‐ray structures for the anthracene and DMA adducts are reported.
Mixed platinum‐gold clusters. Synthesis, structure and properties of PtAu8(PPh3)8(NO3)2
Authors: Bour J. J. , Kanters R. P. F. , Schlebos P. P. J. , Steggerda J. J.
Published: September 2010

PtAu8(PPh3)8(NO3)2 is formed by the reaction of H2 with Au(PPh3)NO3 and either Pt(PPh3)3 or Pt(COD)(NO3)2. The metal frame is a centred crown, with a phosphine bonded to each peripheral metal atom. 31P NMR and Mössbauer spectroscopy showed that Pt is in the centre and that the 8 Au atoms are on the crown. A FAB mass spectrum confirmed the indicated composition and showed that no hydrides are present. In an electrochemical study, the cluster could be reduced in two reversible one‐electron steps at ‐1.14 and ‐1.29 V vs SSCE. The growth of the PtAun clusters is discussed in terms of oxidative addition of H2 to Pt and electrophilic substitution of AuPPh3+.
X‐Ray crystal structure of the ethylzinc enolate of 1‐(2,4‐cyclopentadienyl)‐2‐(diethylamino)‐1‐ethanone, the unexpected reaction product from cyclopentadienyl(ethyl)zinc and ethyl N,N‐diethylglycinate
Authors: Jastrzebski Johann T. B. H. , Boersma Jaap , van Koten Gerard , Smeets Wilberth J. J. , Spek Anthony L.
Published: September 2010

Reaction of cyclopentadienyl(ethyl)zinc with ethyl N,N‐diethylglycinate affords the dimeric ethylzinc enolate (2) of 1‐(2,4‐cyclopentadienyl)‐2‐(diethylamino)‐1‐ethanone in quantitative yield. Its molecular structure was determined by X‐ray crystallography. Crystals of 2 C26H42N2O2Zn2 are monoclinic, space group P21/c, with unit cell parameters a = 7.972(1) Å, b = 15.741(2) Å, c = 11.062(2) Å, β = 91.85(2)°. The crystal structure was solved using standard Patterson methods (Zn) and subsequent difference Fourier techniques. Anisotropic full‐matrix least‐squares refinement with 1989 observed reflections and 160 parameters converged at R = 0.0335.
C‐Stannylated carbohydrate derivatives. Part 1. 6‐Deoxy‐1,2‐O‐isopropylidene‐6‐(triorganostannyl)‐α‐D‐glucofuranose
Authors: Taylor Oonah J. , Wardell James L.
Published: September 2010

The synthesis of 6‐deoxy‐1,2‐O‐isopropylidene‐6‐(triorganostannyl)‐α‐D‐glucofuranose (4) is reported. Compound 4a (R = R′ = Me), reacts with halogens (I2 and Br2) or with Pd(COD)CI2 to give 4 (R = Me, R = X (X = I, Br or Cl) and MeY [Y = I, Br or Pd(CODCl]. The unsaturated sugar, 5,6‐dideoxy‐l,2‐O‐isopropylidene‐α‐D‐xylo‐hex‐5‐enofuranose (6) is formed in the reaction of 4a(‐R = R′ = Me) with CF3CO2H, ClC(O)Z (Z = Ph, Me or OEt), SO2 or (NC)2CC(CN)2

Phenyl‐tin bond cleavage is the predominant, if not sole, reaction of 4b (R = R′ = Ph) with CF3CO2H or I2.
Preparation and structure of triorganotin, triorganolead and tetraphenylantimony derivatives of acetylenedicarboxylic acid, terephthalic acid and dithioterephthalic acid
Authors: Glowacki A. , Huber F. , Preut H.
Published: September 2010

Triorganotin, triorganolead and tetraphenylantimony derivatives of acetylenedicarboxylic acid (H2ADC), terephthalic acid (H2TER) and dithioterephthalic acid (H2DTT) (R3M)2X (M = Sn, Pb; R = Me, Ph; X = ADC, TER, DTT) and (Ph4Sb)2X (X = ADC, TER) were prepared by neutralization of R3MOH or Ph4SbOH with the appropriate acid (X = ADC, DTT) or by reaction of R3MCl or Ph4SbCl with K2TER. The crystal structures of (Me3Sn)2ADC and (Me3Sn)2TER were determined by X‐ray diffraction. The Sn atoms are in slightly distorted trigonal‐bipyramidal environments, with C(Me) in the equatorial plane and O(carboxyl) in apical positions. The carboxylate groups are bridging, leading to the formation of a two‐dimensional polymer of puckered 22‐membered [(Me3Sn)2ADC] and 26‐membered [(Me3Sn)2TER] rings. From vibrational spectra, analogous structures are inferred for solid (Ph3Sn)2ADC, (R3Pb)2ADC (R = Me, Ph), and (Me3Pb)2TER, but structures with unidentate ‐ COO and ‐ COS groups and tetracoordinated Sn or Pb and pentacoordinated Sb are proposed for the other compounds. The DTT ligands are linked by S bonds to M. According to IR and 1H NMR studies the polymeric species dissociate on dissolution so that generally species with unidentate carboxylate groups are present. Sn and Pb in (R3M)2X (X = ADC, TER) are apparently tetracoordinated in CHCl3, but pentacoordinated in DMSO by addition of a solvent molecule.
Characterization of uranyl soaps by spectroscopic and thermal measurements
Authors: Mehrotra K. N. , Sharma Meera , Gahlaut A. S.
Published: September 2010

The infrared and visible spectrophotometric data of uranyl soaps showed that metaloxygen bonds in uranyl soaps are not purely ionic but are partially covalent in character. The X‐ray diffraction patterns confirmed the double‐layer structure with molecular axes perpendicular to the basal plane. The thermal decomposition of these soaps was found to be kinetically of zero order and the energies of activation were found to lie between 14‐58 kJ/mol.
Sulfonation and sulfation on reaction of 1,2‐dihydroxybenzene and its methyl ethers in concentrated aqueous sulfuric acid
Authors: Cerfontain Hans , Coenjaarts Norbert J. , Koeberg‐Telder Ankie
Published: September 2010

The homogeneous sulfonation of 1,2‐dihydroxybenzene (1), its monomethyl (2) and dimethyl ether (3) in concentrated aqueous sulfuric acid at 25°C has been studied and isomer distributions, as well as rate coefficients for the sulfonation of 1–3 and their monosulfonic acids, have been determined. In 73.5‐87.5% H2SO4, 1 yields the 3‐ and 4‐sulfonic acids in a ratio of 25:75, 2 yields the 4‐, 5‐ and 6‐sulfonic acids in a ratio of 46:36:18 in 73.5% H2SO4 and 50:39:11 in 87.5% H2SO4, whereas 3 yields only the 4‐sulfonic acid. The remarkable absence of the 3‐sulfonic acid (< 2%) with the 2‐methoxy substrates 2 and 3 is discussed in terms of conformer populations of the reactants. In sulfuric acid > 87.5% H2SO4, the 4‐sulfonic acid of 1 and the 5‐sulfonic acid of 2 are present in part in the form of their hydrogen sulfate. In that acid region, the 3‐ and 4‐sulforic acids of 1 both yield the 3,5‐disulfonic acid, the 4‐ and 6‐sulfonic acids of 2 both yield the 4,6‐disulfonic acid and the 4‐sulfonic acid of 3 mainly yields the 4,6‐ together with some 4,5‐disulfonic acid.
A partial synthesis of 13‐ethyl‐11‐methylene‐18,19‐dinor‐17α‐pregn‐4‐en‐20‐yn‐17‐ol (desogestrel) based upon intramolecular oxidation of an 11β‐hydroxy‐19‐norsteroid to the 18 → 11β‐lactone
Authors: van den Heuvel M. J. , van Bokhoven C. W. , de Jongh H. P. , Zeelen F. J.
Published: September 2010

A partial synthesis of the 13‐ethyl‐18‐norsteroid desogestrel is reported. The key step in this synthesis is the intramolecular oxidation of 11β‐hydroxyestr‐5‐ene‐3,17‐dione cyclic bis‐(1,2‐ethanediyl acetal) 3 with Pb(OAc)4 and iodine to 3,3:17,17‐bis[1,2‐ethanediylbis(oxy)]‐11β‐hydroxyestr‐5‐en‐18‐oic acid γ‐lactone 2.

The 13‐COOH group was then converted into a 13‐ethyl group by a Grignard reaction with methyl‐magnesium bromide followed by Wolff‐Kishner reduction of the 13‐acetyl group thus formed.
Synthesis of vinca alkaloids and related compounds XXXVIII: Formation of dimers under Polonovski reaction conditions
Authors: Moldvai István , Kálmán Alajos , Szántay Csaba , Tóth Gábor , Vedres András
Published: September 2010

The dimeric products (la‐c) have been prepared by treatment of N‐oxides derived from some indole alkaloids. Their structures have been elucidated by detailed NMR investigations and the structure of 1c determined by X‐ray analysis. The importance of the E2‐type trans‐axial elimination of the N‐acyloxy intermediate in the dimer formation has also been established. The iminium salts 4a‐b and the derived pseudocyanide 6 have been prepared.
Enzymes that do not work in organic solvents: Too polar substrates give too tight enzyme‐product complexes
Authors: Kieboom Antonius P. G.
Published: September 2010

The possible effect of hydration of both the enzyme active site and the substrate or product on enzyme complex formation has been evaluated.

Replacement of water by organic solvents in the case of highly polar substrates, e.g. carbohydrates, phosphates, sulfates, leads to such an enhancement of enzyme‐substrate and/or enzyme‐product complex stability that there is no measurable conversion. The very low rate of dissociation of the enzyme‐product complex simply prevents these polar‐substrate converting enzymes to be catalytically effective in apolar media. Proper less‐polar substrates, on the other hand, might be more promising.
Syntheses of some N‐(pyrazinecarbonyl) amino acids and peptides
Authors: Kočvar Marijan , Polanc Slovenko , Verček Bojan , Tišler Miha
Published: September 2010

Derivatives of some amino acids, having a pyrazinecarbonyl or 3‐aminopyrazinecarbonyl radical, have been synthesized and some peptides prepared. In the case of the 3‐aminopyrazinecarbonyl derivatives, condensed pyrimidines, i.e. 4(3H)‐pteridinone derivatives, could be prepared.
Oxidation of 1‐hydroxyazetidines to four‐membered cyclic nitrones and β‐lactams
Authors: van Elburg P. A. , Reinhoudt D. N.
Published: September 2010

The 1‐(benzyloxy)azetidines 7a‐c and 16a,b were synthesized by reductive cyclization of the corresponding oximes 5a‐c and 14a‐d. Oxidation of the 1‐hydroxyazetidines 8a‐c and 17 with PbO2 afforded the corresponding four‐membered cyclic nitrones 18a‐c and the bicyclic four‐membered nitrones 18d and 18e, which were characterized as the cycloadducts 19a‐c and 20 by reaction with dimethyl acetylenedicarboxylate. Pb(OAc)4 oxidation of the monocyclic l‐hydroxy‐azetidine 8a gave 1,4‐bis(acetyloxy) β‐lactam 22a and 1,4,4‐tris(acetyloxy) β‐lactam 23a, while oxidation of the 1‐hydroxyazetidines 8b,c gave exclusively the 1,4‐bis(acetyloxy) β‐lactams 22b and 22c. Oxidation of bicyclic l‐hydroxyazetidine 17 with Pb(OAc)4 afforded the bicyclic bis(acetyloxy) β‐lactam 21.
Photochemical isomerizations of 2‐vinyl‐2‐phenylcyclohexanone; ketene, alkenal and 1,3‐acyl shift product formation from the excited singlet state
Authors: Koppes Margareth J. C. M. , Cerfontain Hans
Published: September 2010

The photochemistry of 2‐vinyl‐2‐phenylcyclopentanone (1) and 2‐vinyl‐2‐phenylcyclohexanone (2) has been studied under conditions of both direct (λ 300 nm) and triplet‐sensitized irradiation. Whereas compound 1 is photostable, compound 2 yields three photochemical isomerization products upon direct irradiation, viz. the ring‐expanded phenylcyclooctenone 8 (ϕ = 0.43), (E)‐and (Z)‐phenyloctadienals 9 (ϕ = 0.06 for each geometric isomer) and a ketene, which, in 2‐propanol, affords the corresponding ester 10 (ϕ = 0.08). In these rearrangements, the intermediacy of a common singlet diradical, formed by initial α‐cleavage, is suggested. This diradical yields the alkenals and ketene by intramolecular 1,5‐H shifts and cyclizes to the 1,3‐AS 8 and the starting material.
Sulfonation of chloro‐ and dichloroanisoles with concentrated aqueous sulfuric acid and sulfur trioxide. Demethylation of chloroanisolesulfonic acids in sulfuric acid systems
Authors: de Wit Peter , Cerfontain Hans
Published: September 2010

The nine chloro‐ and dichloroanisoles have been sulfonated with sulfuric acid. The observed sulfonic acid isomer distributions are determined mainly by the ortho‐ and para‐ directing effect of the methoxy substituent. In the reaction with sulfuric acid, the initially formed chloro‐ and dichloroanisolesulfonic acids are demethylated to give the corresponding phenolsulfonic acids. Demethylation occurs only in those cases where the methoxy substituent is sterically hindered by an o‐chloro and/or o‐sulfo substituent. Reaction of 2,3‐ and 3,5‐dichloroanisole with fuming sulfuric acid yields initially the 4,6‐ and 2,4‐disulfonic acids, respectively. The disulfonic acids are converted to the corresponding hydrogen sulfates either by direct sulfodemethylation or by protodemethylation followed by subsequent sulfation. The 2,3‐dichloro‐4,6‐disulfophenyl hydrogen sulfate cyclizes to the 1,3,2,4‐benzodioxadithiin 2,2,4,4‐tetraoxide 4.

The sulfonation of the chloro‐ and dichloroanisoles with SO3 in the solvents nitromethane or CCl3F leads only to sulfodeprotonation.
Sulfonation and sulfation in reactions of C‐methylated phenols and anisoles with sulfur trioxide. 4‐Substituted phenyl hydrogen sulfates: Effective reagents for transsulfonation
Authors: Goossens Hans D. , Lambrechts Hans J. A. , Cerfontain Hans , de Wit Peter
Published: September 2010

The sulfation and sulfonation of the methyl‐ and dimethylphenols with 0.9 and 4.0 equiv. of SO3 in nitromethane at 0°C have been studied. On using 0.9 equiv. of SO3, the sulfonic acid product distributions are determined by the ortho‐ and para‐directing effect of the activating hydroxy substituent. In the reactions with 4.0 equiv. of SO3, the sulfonic acid product distributions are affected by the predominant initial formation and the subsequent sulfonation of the corresponding phenyl hydrogen sulfates, of which the bulky OSO3H substituent is electronically deactivating and (mainly) para‐directing. For comparison, the sulfonation of the methylanisoles, phenyl methanesulfonate and 2,3‐dihydrobenzofuran was also studied.

The sulfonation of 1,3‐dimethoxybenzene in (2H8)dioxane at 17.0°C has been studied using 4‐substituted phenyl hydrogen sulfates as transsulfonating agents. The transsulfonation was found to be first order with respect to the phenyl hydrogen sulfates and independent of the 1,3‐dimethoxybenzene concentration. The reaction constant of the transsulfonation reaction was determined to be ρ = 2.0 ± 0.2.
Stéréosélectivité de la radioréduction γ d'alkylcyclohexanones
Authors: Alipour E. , Micheau J. C. , Paillous N.
Published: September 2010

La radioréduction γ de cyclohexanones substituées conduit principalement aux deux cyclohexanols diastéréoisomères correspondants. La stéréosélectivité de cette réaction dépend de la concentration en cétone. L'existence de deux radicaux pyramidaux diastéréoisomères, précurseurs des cyclohexanols, est à l'origine des stéréosélectivités observées. Un processus de solvatation sélective de l'OH radicalaire a été proposé pour rendre compte des variations de stéréosélectivité avec la concentration en cétone.

γ Radioreduction of substituted cyclohexanones mainly leads to diastereoisomeric cyclohexanols. The stereoselectivity of radioreduction depends on ketone concentration. The assumption of two pyramidal diastereoisomeric hydroxycyclohexyl radicals explains the observed stereoselectivity. A selective solvation process of the hydroxy group of the radical has been proposed to account for the variations of stereoselectivity with ketone concentration.
Synthesis of L‐glycero‐D‐manno‐heptose
Authors: Boons G. J. P. H. , van der Klein P. A. M. , van der Marel G. A. , van Boom J. H.
Published: September 2010

The easily accessible benzyl 2,3,4‐tri‐O‐benzyl‐α‐D‐manno‐hexodialdo‐1,5‐pyranoside (2) can be converted, in a highly stereoselective manner, by the two‐step Tamao method to benzyl 2,3,4‐tri‐O‐benzyl‐β‐L‐glycero‐D‐manno‐heptopyranoside (4a).
Synthesis of bis[2‐(dimethylarsino)ethyl]amine (daea) and its complexation with rh(i) and Pd(II)
Authors: Jaouhari R. , Edwards P. G.
Published: September 2010

The preparation of the new chelating ‘HYBRID’ ligand containing secondary amine and tertiary arsine donors HN(CH2CH2AsMe2)2 is described. The simple coordination chemistry with [RhCl(COD)]2 (COD = cycloocta‐1,5‐diene) and Na2PdCl4 to give square planar complexes is also reported.
Preparation and properties of S,S‐diphenyl amino acid phosphorodithioates
Authors: Kuyl‐Yeheskiely E. , Tromp C. M. , Geluk A. , van der Marel G. A. , van Boom J. H.
Published: September 2010

S,S‐diphenyl phosphorodithioates of appropriately protected serine and tyrosine have been prepared. In the case of serine, neighbouring group participation of a free N‐or C‐terminus on the corresponding triester functions leads to the formation of aziridine and phosphoserine derivatives, respectively.
Sulfonation and sulfation on reaction of 1,4‐dihydroxybenzene and its methyl ethers in concentrated sulfuric acid
Authors: Cerfontain Hans , Koeberg‐Telder Ankie
Published: September 2010

The homogeneous reactions of 1,4‐dihydroxybenzene (1), its monomethyl (2) and dimethyl ether (3) and 2‐3‐sulfonic acid in 68‐105% H2SO4 at 25°C have been studied and isomer distributions and rate coefficients for the various subsequent sulfonations, as well as the equilibrium data for the sulfation (‐OH⇌ ‐OSO3H), are reported. For 2, the ratio of 2‐ to 3‐sulfonation decreases upon increasing the sulfuric acid concentration from 68‐98.5% H2SO4, due to a gradual change‐over in the effective sulfonating entity from H3SO4 + to H2S2O7. For 1‐2‐sulfonic acid (1‐2‐S), 2‐2‐S and 2‐3‐S, the ratios of 5‐ to 6‐sulfonation are all ca. 25:75, whereas 3‐2‐S only yields the 5‐sulfonic acid. Demethylation of the sulfonic acids of 2 and 3 in ≤98.5% H2SO4 is of minor importance, but plays a major role in 105.0% H2SO4, the eventual products being the bis(hydrogen sulfate)s 10 and 15, the tricyclic bis(sulfate sulfonate anhydride) 11 and the bicyclic hydrogen sulfate 16.

Mechanisms for the sulfodemethylation and for the cyclization of the 2‐sulfophenyl hydrogen sulfate moiety to the 1,3,2,4‐benzodioxadithiin 2,2,4,4‐tetraoxide system are proposed.
Acetalation studies. Part VI. Concerning the effects of ultrasound on the benzylidenation of some alkyl D‐glycopyranosides
Authors: Chittenden Gordon J. F.
Published: September 2010

The effects of ultrasound on conventional Freudenberg‐type benzylidenation reactions of some alkyl D‐glycopyranosides is described. A considerable enhancement in the rates of formation of the expected acetals was observed. The pure products were obtained in good yields. Some of the crude air‐dried products were suitable for direct derivatisation.
Synthesis of a cell wall component of haemophilus (actinobacillus) pleuropneumoniae type 2
Authors: Veeneman G. H. , Brugghe H. F. , Hoogerhout P. , van der Marel G. A. , van Boom J. H.
Published: September 2010

Coupling of properly protected repeating tetrasaccharide units of Haemophilus (Actinobacillus) pleuropneumoniae could be realized by regioselective phosphorylation.
Evidence of an ordered columnar mesophase in peripherally octa‐n‐alkoxy‐substituted phthalocyanines
Authors: van der Pol J.F. , Neeleman E. , Zwikker J.W. , Drenth W. , Nolte R.J.M.
Published: September 2010

Liquid crystalline phthalocyanines with eight n‐alkoxy chains have been synthesized and their mesophase structures determined by X‐ray diffraction. The mesophases appear to be of the Dho type. Reasons for the preference of ordered columns are discussed.
[(3‐13C)‐3‐Aminopropyl]triethoxysilane; synthesis and spectral characterization of 13C‐substituted compounds
Authors: Jenneskens Leonardus W. , van den Berg Ellen M. M. , Heemskerk Bram , Lugtenburg Johan
Published: September 2010

The synthesis of [(3‐13C)‐3‐aminopropyl]triethoxysilane (la) from (1‐13C)acrylonitrile (4a) is described. The latter was prepared from potassium (13C)cyanide (13C‐enrichment > 99%) and 2‐bromoethanol (7). The spectroscopic properties of the 13C‐substituted compounds are discussed.
1,3,5‐Hexatriene photochemistry. The photo‐isomerization of (Z)‐3‐(6′,6′‐dimethyl‐2′‐methylenecyclohexylidene)‐1‐propene
Authors: Geenevasen Jan A. J. , Cerfontain Hans
Published: September 2010

The photo‐isomerization of (Z)‐3‐(6′,6′‐dimethyl‐2′‐methylenecyclohexylidene)‐1‐propene [(Z)‐3a] has been studied under conditions of triplet photosensitization, using benzophenone as sensitizer, and direct irradiation with λ 254 nm. Under the former conditions, only Z‐E isomerization is observed leading to a photostationary state with {[Z]/[E]}pss = 1.77 and 1.50 for benzene and chloroform as the respective solvent. Upon direct irradiation, the primary products are (E)‐3a, the tricyclodecene 11a and the bicyclooctene 12a, formed in an initial ratio of 9/2.0/1.0. The two polycyclic isomers 11a and 12a apparently result from the excited singlet state. NOE 1N NMR measurements illustrate hat (Z)‐3a is present mainly in a s‐transoid conformation.
Photochemistry of two diphenyl β,γ‐enones and a series of methyl‐ and phenyl‐substituted α‐phenyl ketones
Authors: Koppes Margareth J. C. M. , Crabbendam Astrid M. , Cerfontain Hans
Published: September 2010

The photochemistry of the diphenyl β,γ‐enones2and3and the methyl‐ and phenyl‐substituted α‐phenyl ketones4‐9has been studied, using mainly benzene as solvent. Irradiation of2with λ 300 nm leads to the 1,3‐acyl shift (1,3‐AS) product17, relatively small amounts of the decarbonylation products15and16, and the photo‐oxidation products benzophenone (18) and the α,β‐unsaturated aldehyde19. Direct irradiation of the 1,3‐AS product17yields15, 16, 18and19, but no2.

Direct irradiation of 3 with λ 350 nm leads mainly to the formation of 1,3‐AS products (E)‐ and (Z)‐22, the decarbonylation products (E)‐ and (Z)‐20and21and, in addition, a small amount of thecis‐di‐π‐methane isomer23.

Direct irradiation of the substituted α‐phenyl ketones4, 5, 8and9with γ 300 nm leads predominantly to the formation of the radical coupling products 2,3‐butanedione and24‐27, respectively, whereas6and7yield 1,2‐diphenyl‐1,2‐ethanedione and the respective24and25. The acetone‐sensitized irradiation of4leads to 4‐phenyl‐2‐butanone (33) in addition to 2,3‐butanedione and 1,2‐diphenylethane (24).
An unusual 1,2‐silyl shift during the reaction of an α‐oxo sulfine with an allylsilane
Authors: Rewinkel J. B. M. , Zwanenburg B. , García‐Granda S. , Beurskens P. T. , Raaijmakers R.
Published: September 2010

The reaction of 1‐oxo‐2‐thioxo‐indane S‐oxide 1 with 1‐(trimethylsilyl)‐1 H‐indene 2 gave endo‐2‐oxo‐7‐(trimethylsilyl)‐5,6‐benzo‐2‐thiabicyclo[2.2.1]hept‐5‐ene‐3‐spiro‐2′‐indan‐1′‐one 3 as the sole product. The crystal and molecular structure of the corresponding sulfone, 4, C21H22O3SSi, was established by X‐ray diffraction analysis. The endo structure of the sulfoxide 3 was deduced from 1H NMR spectra. The formation of the product 3 can be explained by invoking a 1,2‐silyl shift.
The rate‐determining step in the epoxidation of alkenes by the cytochrome P‐450 model manganese(III) porphyrin/hypochlorite
Authors: van der Made A. W. , Groot P. M. F. C. , Nolte R. J. M. , Drenth W.
Published: September 2010

Using low‐temperature trapping experiments with 1,1‐diphenyl‐2‐picrylhydrazine monitored by UV/Vis spectroscopy, it is shown that the rate‐determining step in the epoxidation of alkenes by hypochlorite, catalysed by manganese(III) porphyrins, involves the formation of the active oxo‐manganese species [(P)MnO]+.
8,16‐ And 8,18‐methanobacteriorhodopsin. Synthesis and spectroscopy of 8,16‐ and 8,18‐methanoretinal and their interaction with bacterioopsin
Authors: van der Steen R. , Biesheuvel P. L. , Lugtenburg J. , Erkelens C. , Mathies R. A.
Published: September 2010

8,16‐ And 8,18‐methanoretinal with a locked 6‐s‐trans and a 6‐s‐cis conformation have been synthesized and characterized. Their 9‐Z and 13‐Z isomers could also be prepared, in contrast to the 11‐Z. 8,16‐Methanoretinal easily binds with bacterioopsin (bO) to form a bacteriorhodopsin analogue which closely resembles natural bacteriorhodopsin (bR) (λmax, light‐dark adaptation and proton pump action). The interaction of 8,18‐methanoretinal with bO is complex. These findings give additional support to the fact that in bR the chromophore occurs in the planar 6‐s‐trans conformation. Approximately 1200 cm−1 of the opsin shift in bR (5100 cm−1) arises because the chromophore changes upon binding to the protein from a 40° twisted 6‐s‐cis to a planar 6‐s‐trans conformation. Both 8,16‐ and 8,18‐methano bR have a ∼3900 cm−1 opsin shift, since the C6‐C7 conformation does not allow protein‐induced changes. This is consistent with the idea that the opsin shift is mainly due to the perturbation of the Schiff base region.
Para‐nitrosation of a primary and a secondary amine in aqueous solution: 2,6‐di‐tert‐butyl‐4‐nitrosoaniline and N, 2‐di‐tert‐butyl‐4‐nitrosoaniline
Authors: Hoefnagel M. A. , Wepster B. M.
Published: September 2010

2,6‐Di‐tert‐butylaniline 1 and N, 2‐di‐tert‐butylaniline 2 yield their 4‐nitroso derivatives on treatment with nitrous acid in aqueous media. Electronic spectra in various solvents show that these products, as well as 4‐nitrosoaniline and 4‐nitroso‐N‐methylaniline, have the nitroso‐amino structure and not the prototropic quinonoid form.
Cation complexation with functionalized 9‐arylacridinium ions: Possible applications in the development of cation‐selective optical probes
Authors: Jonker S. A. , Ariese F. , Verhoeven J. W.
Published: September 2010

Absorptive and emissive properties of 9‐arylacridinium ions 2‐6 have been studied and shown to be dependent on the electron‐donating properties of the aryl group. While for 2 and 3 the first excited state remains largely localized on the acridinium chromophore, interaction of this chromophore with the electron‐donor‐substituted aryl group in 4‐6 produces a low‐lying intramolecular charge‐transfer state, resulting in a state inversion. This state inversion leads to the appearance of a new long‐wavelength absorption in the visible region and to complete quenching of the acridinium fluorescence. Protonation of the amino function in 4‐6 cancels this state inversion, thereby causing a dramatic chromofluoroionophoric effect, i.e. cation‐induced change of both colour and fluorescence properties. Replacing the amino function by an aza crown ether resulted in system 7, which displays similar effects, not only upon protonation but also upon metal ion complexation.
The reaction between a phosphole and diphenylketene at high pressure; an unexpected outcome
Authors: Isaacs Neil S. , El‐Din Ghazi Najem , Drew Michael G. B.
Published: September 2010

The reaction between 3,4‐dimethyl‐l‐phenylphosphole and diphenylketene at 10 kbar, 25 °C, leads to the formation not of a 1:1 cycloadduct but to a novel spirodioxaphosphorane formed from four molecules of diphenylketene and one of phosphole which loses in the process all its ring carbons. The structure is established by X‐ray crystallography.
Redox properties of cerium‐exchanged Y‐zeolites
Authors: Floor M. , Kieboom A. P. G. , van Bekkum H.
Published: September 2010

The oxidation of cerium(III)‐exchanged zeolite NaY (exchange level 24‐91%) with aqueous hydrogen peroxide and oxygen has been studied. The fraction of Ce(IV) produced decreases with increasing Ce content of the zeolites. Hydrogen peroxide is catalytically decomposed by the Ce(III)/Ce(IV) redox couple with formation of an equilibrium level of a Ce(IV) hydroxide species. Oxidation with oxygen at temperatures higher than 400 K yields an oxycerium(IV) complex. The latter NaCe(IV)Y zeolite effects oxidative glycol cleavage of 2,3‐dimethyl‐2,3‐butanediol to acetone. Activation in oxygen restored its oxidizing capacity. Thus, the oxygen‐activated NaCe(IV)Y zeolite is a regenerable glycol‐cleaving oxidant. The H2O2‐oxidized NaCe(IV)Y is not active in glycol‐cleavage oxidiation.
Transition metal compounds of 5,7‐dimethyl[1,2,4]triazolo[1,5‐a]pyrimidine (dmtp). X‐ray structures of trans‐tetraaquabis(dmtp‐N3)nickel(II) diiodide dihydrate and trans‐diaquatetrakis(dmtp‐N3)nickel(II) bis(triiodide) bis‐dmtp
Authors: Lenstra A. T. H. , Slot H. J. Bruins , Beurskens Paul T. , Haasnoot J. G. , Reedijk J.
Published: September 2010

5,7‐Dimethyl[1,2,4]triazolo[1,5‐a]pyrimidine (dmtp) has been used as a ligand for nickel(II) and cobalt(II) chloride, bromide, iodide and triiodide. The halides yield compounds of composition trans‐[M(dmtp)2(H2O)4](H2O)2X2, the triiodides having the composition trans‐[M(dmtp)4(H2O)2](dmtp)2(I3)2. The IR spectra of he halides are all mutually isomorphous, differing from those of the triiodides. Spectroscopic properties agree with octahedrally coordinated metal ions with MN2O4 and MN4O2 chromophores, respectively. The crystal structures of two representative compounds, i.e. the nickel iodide and the nickel triiodide compounds, are described.

[Ni(dmtp)2(H2O)4](H2O)2I2 is triclinic, P−1, a 8.175(1) Å, b 8.263(3) Å, c 9.628(2) Å), α 85.60(2)°, β 81.84(2)°, γ 82.06(2)°, Z 1, dc 1.870 Mg.m−3, R 0.084 based on 2516 reflections. Ni2+ is octahedrally coordinated by two N(3)‐bonded dmtp ligands (trans‐oriented) with Ni‐N 2.080(6) Å) and four water molecules with Ni‐O 2.067(6) Å and 2.094(6) Å, respectively. The iodides and the remaining water molecules are retained in the lattice, through extensive hydrogen bonding. [Ni(dmtp)4(H2O)2](dmtp)2(I3)2 is triclinic, P−1, a 12.428(2) Å, b 14.852(2) Å, c 8.795(2) Å, α 103.27(2)°, (3 108.80(3)°, γ 89.73(2)°, Z 1, dc 1.944 mg.m−3, R 0.092 based on 3724 reflections. Ni2+ is octahedrally coordinated by two water molecules in a trans orientation with Ni‐O 2.13(1) Å and by four N(3)‐bonded dmtp ligands with Ni‐N 2.07(2) Å and 2.09(2) Å, respectively. The triiodide ions are linear with II bonds of 2.918(3) Å and 2.884(3) Å. The compound forms a lattice adduct with two extra dmtp molecules, with stacking interactions.
Synthesis and NMR spectroscopy of stable isotope‐labelled phenols and L‐tyrosines
Authors: Winkel C. , Aarts M. W. M. M. , van der Heide F. R. , Buitenhuis E. G. , Lugtenburg J.
Published: September 2010

The syntheses of (17O)phenol from (17O)water, (18O)phenol from (18O)water, (1‐13C)‐phenol and (4‐13C)phenol from (2‐13C)acetone and (2‐13C)phenol and (3‐13C)phenol from (1‐13C)‐acetone with high isotopic enrichment are described. The labelled phenols are converted into their corresponding L‐tyrosines by the bacterium Erwinia herbicola. A full analysis of the 1H and 13C NMR spectra of phenol and L‐tyrosine is reported.
Conformational analysis of some chiral catalysts of the cinchona1 and ephedra2 family. The alkaloid catalyzed addition of aromatic thiols to cyclic α,β‐unsaturated ketones
Authors: Dijkstra Gerard D. H. , Kellogg Richard M. , Wynberg Hans
Published: September 2010

The minimum energy conformations of quinine, quinidine, ephedrine and N‐methyl‐ephedrine have been calculated using molecular mechanics and semi‐empirical techniques. Conformational data for quinine and quinidine in solution have been obtained by 2D‐NMR. No evidence has been found for an earlier proposed conformational change of the catalysts3 in the asymmetric Michael addition between cycloalkenones and aromatic thiols. The preferred orientations between 4‐methylbenzenethiol and quinine have been predicted with molecular docking calculations; they are in good agreement with NOESY NMR data. The results obtained by this combined NMR and molecular modelling approach suggest a new model for the transition state of alkaloid‐catalyzed addition of aromatic thiols to 2‐cyclohexenone.
The gas‐phase thermolyses of di‐, tri‐ and tetrachloroethene in hydrogen between 828 and 1050 K
Authors: Manion Jeffrey A. , Louw Robert
Published: September 2010

The thermolyses in hydrogen of 3–6 vol. % of 1,1‐dichloroethene, (E)‐1,2‐dichloroethene, trichloroethene and tetrachloroethene have been examined in a tubular flow reactor at atmospheric pressure between 828 and 1068 K. Major products are HCl, lower chlorinated ethenes, ethyne, ethene, ethane and methane. Chlorinated benzenes, major products in the straight pyrolysis of these compounds, are formed in only small amounts, the reasons for which are discussed. Dechlorination occurs in part via a chain mechanism involving H‐atom addition and ipso substitution of Cl. A second route, molecular elimination of HCl, also occurs but appears to become less important for the more chlorinated substrates. At 880 K, addition of a H atom to the monochloro‐substituted carbon of C2HCl3 takes place ca. 8 × more rapidly than it does to the dichloro site. The hydrogen‐atom concentration is somewhat greater than that calculated from equilibrium dissociation of H2 and varies by a factor of ca. 4 for the various substrates. Differences in hydrogen‐atom concentration are larger at lower temperatures, apparently due to the presence of relatively unreactive radicals in some systems, which lead to increased chain termination.
Studies on the micellar behaviour of praseodymium soaps
Authors: Mehrotra K. N. , Sharma Meera , Gahlaut A. S.
Published: September 2010

Colourimetric and magnetic measurements show that praseodymium soaps are ionic in nature and that the praseodymium ions are in trivalent state. Viscosity and colourimetric results show that the soap molecules do not aggregate below the CMC. Viscosity results have been interpreted in the light of well known equations proposed by Einstein, Vand, Moulik and Jones‐Dole.
An ESR study on electron‐capture phosphorus‐centred radicals in solid matrices of alkyl/phenyl phosphine sulfides and selenides
Authors: Aagaard Olav M. , Janssen René A. J. , Buck Henk M.
Published: September 2010

A low‐temperature ESR study on electron‐capture radicals in X‐irradiated alkyl/ phenylphosphine chalcogenides is presented. In general, exposure of solid R(3‐n)Phn PX derivatives (R = alkyl, Ph = phenyl, X = S, Se, n = 1, 2) to X‐rays gave ESR spectra assigned to the corresponding radical anions, in which the unpaired electron is located in an antibonding P‐X σ* orbital. For two of the compounds studied (Me2PhPSe and MePh2PSe), however, no phosphoranyl radicals could be observed. For methylphenyl‐n‐propylphosphine selenide, a single‐crystal ESR analysis of the σ* radical anion is presented, giving detailed information on its electronic and geometric structure. It is found that the unpaired electron resides in a PSe anti‐bonding σ* orbital, whose direction almost parallels the parent PSe bond. Aspects of radiation damage mechanisms and phosphoranyl radical formation in phosphine chalcogenides are discussed.
Dinuclear copper(I) benzoato quinoline complexes as intermediates in the copper‐quinoline decarboxylation reaction
Authors: Aalten Henk L. , van Koten Gerard , Tromp Jeroen , Stam Casper H. , Goubitz Kees , Mak Arjen N. S. , van der Kerk‐van Hoof Anca
Published: September 2010

The reaction of both the novel mixed trinuclear organo‐organic copper(I) species [Cu3(C6H2Me3‐2,4,6)(μ‐O2CC6H5)2] (1) and [Cu(μ‐O2CC6H5)]4 (2a) with quinoline in toluene or diethyl ether yields the dimeric 1:2 copper/quinoline complex [Cu(μ‐O2CC6H5)(NC9H7)2]2 (3a). The reactions of methyl‐substituted copper(I) benzoates, [Cu(μ‐O2CC6H4Me‐x)]4 (x = 2, 2b; x = 3, 2c; x = 4, 2d), with quinoline in toluene or diethyl ether, however, afford the 1:1 copper/quinoline complexes [Cu(μ‐O2CC6H4Me‐x)(NC9H7)]2 (x = 2, 4b; x = 3, 4c; x = 4, 4d).

The structure of complex 4b, determined by a single‐crystal X‐ray diffraction study, shows a dicopper(I) unit doubly bridged by two benzoato units [Cul…Cul* = 2.667(1) Å]. At each copper site, the CuO bonds to the bridging benzoato groups differ considerably [Cul‐Ol = 1.923(5) Å; Cul‐O2* = 2.134(5) Å]. Coordination of a quinoline at each copper site [Cul‐Nl = 1.952(5) R] produces a distorted trigonal arrangement.

Crystallization of the 1:2 copper‐quinoline complex 3a led to formation of crystals of the dimeric 1:1 copper/quinoline complex [Cu(μ‐O2CC6H5)(NC9H7)]2, 4a. The structure of 4a is similar to that of 4b [Cul…Cul* = 2.638(2) Å Cul‐Ol = 1.945(6) Å Cul‐O2* = 2.107(6) Å Cul‐Nl = 1.939(7) Å]. Since complexes 3 and 4 can be expected to be similar to the intermediates formed in the copper‐quinoline decarboxylation reaction, the reactivity of 3 and 4 at elevated temperatures in non‐coordinating solvents has been studied. It was found that the decarboxylation reaction requires more than one equivalent of quinoline per copper atom. An improved mechanism is presented for the copper‐quinoline decarboxylation reaction involving dinuclear copper(I) complexes as intermediates.
Synthesis of an immunologically active component of the extracellular polysaccharide produced by Aspergillus and Penicillium species
Authors: Veeneman G. H. , van Boom J. H. , Notermans S. , Hoogerhout P.
Published: September 2010

The synthesis of an immunologically active component of the extracellular polysaccharide produced by Aspergillus and Penicillium species, in the form of tetrameric β(1→ 5) interlinked D‐galactofuranoside, is described. Key reactions are the assemblage of a galactofuranosyl donor, having a selective removable protecting group at C‐5, and a stepwise elongation‐deprotection procedure. Furthermore, the synthesis of β(1→ 2), β(1 → 3) and β(1 → 6) D‐galactofuranosyl dimers is reported.
Synthetic approaches to glutinosone
Authors: Banerjee Ajoy K. , Pita‐Boente Maria I.
Published: September 2010

The dienone 4 was converted to ketal ketone 6 by ketalization and reduction with lithium in liquid ammonia. The tosylhyrazone of 6, on treatment with lithium diisopropylamide, afforded the olefin 9 which was converted to the bromohydrin 12 with N‐bromosuccinimide. Oxidation of bromohydrin 12 with lead tetraacetate in benzene afforded the bromo ether 16, whose transformation to epoxy ketone 3 was achieved by heating with tri‐n‐butyltin hydride in methanol followed by deketalization.
Synthesis of three retinal models, including the 10‐s‐cis‐locked retinal, all‐E‐12,19‐methanoretinal
Authors: Groesbeek M. , van der Steen R. , van Vliet J. C. , Vertegaal L. B. J. , Lugtenburg J.
Published: September 2010

All‐E‐12,19‐methanoretinal (1) is distinguished by the presence of the locked 10‐s‐cis conformation in the cyclohexadiene ring in the conjugated chain. 1 has been prepared together with its 13‐Z isomer in an overall yield of 0.5%. 1 and 13‐Z‐1 photochemically interconvert in a clean way. In this system, only photoisomerization around the C13  C14 double bond is observed. In the photostationary state, the 13‐Z isomer is predominant. All‐E‐12‐ethyl‐19‐methylretinal (2) and all‐E‐12‐ethylretinal (3) were prepared in good overall yields (20% and 30%) from β‐ionone using the novel synthon, 3‐methyl‐4‐(diethylphosphono)‐2‐hexenenitrile (11). The photochemistry of these retinal derivatives is very similar to that of retinal. The 9‐Z, 11‐Z and 13‐Z isomers of 2 and 3 were photochemically prepared. The 13C NMR spectra of these new compounds gave information about the structural elements of alkyl groups in conjugated systems and about the conformation of the conjugated chain.
Synthesis of indoles using (N‐arylaminomethyl)diphenylphosphine oxides
Authors: Zorgdrager Jan , Broekhof Nico L. J. M. , van der Gen Arne
Published: September 2010

A new route for the synthesis of 1,3‐disubstituted indoles, based on (N‐arylaminomethyl)‐diphenylphosphine oxide (1) chemistry, is described. Adducts 2, obtained by addition of the carbanions from 1 to aldehydes, were treated with p‐toluenesulfonic acid to form the desired indoles 4 in good yields, without isolation of the intermediate amino ketones 3.
Reactions of a series of methyl ethers of the trihydroxybenzenes and three dimethoxyphenyl methanesulfonates with sulfur trioxide. The effect of initial sulfation on the sulfonation product distribution
Authors: Cerfontain Hans , Ansink Harold R. W. , Coenjaarts Norbert J. , de Graaf Erik J. , Koeberg‐Telder Ankie
Published: September 2010

The sulfation and sulfonation of a series of mono‐, di‐ and trimethyl ethers of the trihydroxybenzenes with SO3 have been studied and the product distributions are reported. As for the trimethoxybenzenes, 1,2,3‐trimethoxybenzene (4) yields the 4‐sulfonic acid (4‐4‐S) and, upon further sulfonation, 4‐4,6‐S2. 1, 2, 4‐Trimethoxybenzene (7) yields a mixture of the 5‐sulfonic acid and its anhydride. 1, 3, 5‐Trimethoxybenzene (11) yields the 2‐sulfonic acid and, upon further sulfonation, 11‐2,4‐S2.

1, 2‐Dihydroxy‐3‐methoxybenzene (1) with up to 2.0 equiv of SO3 yields the 6‐sulfonic acid. For 2, 6‐dimethoxyphenol (2), the ratio of 3‐ to 4‐sulfonation increases from 1.04 to 7.1 on using 4.0 instead of 0.9 equiv of SO3, due to initial formation of the hydrogen sulfate derivative and subsequent ring sulfonation of that species. 3,4‐Dimethoxyphenol (5), upon sulfonation with both 1.0 and 4.0 equiv of SO3, only yields the 6‐sulfonic acid. 1,3‐Dihydroxy‐5‐methoxybenzene (8), upon sulfonation with 1.0 equiv of SO3, yields 8‐2‐S and 8‐4‐S in a 1:1 ratio in addition to 20% of the hydrogen sulfate of 8. Upon further reaction, a mixture of 8‐2,4(= 2,6)‐S2 and 8‐4,6‐S2 is formed. 3,5‐Dimethoxyphenol (9), upon reaction with 1.0 equiv of SO3, yields 9‐2‐S, whereas with 4.0 equiv of SO3, a 32:68 mixture of 9‐2‐S, 9‐4‐S is obtained. The reactions with SO3 of three dimethoxyphenyl methanesulfonates, as model compounds for the corresponding hydrogen sulfates, which are the initial products formed by sulfation of the corresponding phenols, have also been studied. The observed sulfonic acid product distributions are discussed on the basis of the Curtin‐Hammett principle.
The acetalization of glyoxal by vicinal diols
Authors: Sangsari Farid Hamedi , Chastrette Francine , Chastrette Maurice , Blanc Alain , Mattioda Georges
Published: September 2010

The structure and stereochemistry of products obtained when vicinal diols are allowed to react with glyoxal were established with the aid of 13C NMR structure relationships. Hemiacetalization yields 1,4‐dioxane‐2,3‐diols regardless of the diol reacted. The course of acetalization depends on the structure of the diol: trans‐1,2‐cyclohexanediol and analogs yield only 1,4,5,8‐tetraoxadecalins as acetals, whereas cis‐1,2‐cyclohexanediol and 1,2‐ethanediol yield mixtures containing mostly 2,2′‐bi‐1,3‐dioxolanes. The isomeric distribution of products depends on the reaction conditions.