bluuebunny/crossref_metadata_2025 huggingface dataset:
Palladium‐catalysed reactions of unsaturated compounds in non‐aqueous solvents: The oligomerization of butadiene using π‐allylpalladium acetate as catalyst
Authors: Medema D. , van Helden R.
Published: September 2010

With π‐allylpalladium acetate as catalyst, butadiene is converted in benzene solution into the linear trimer n‐dodecatetraene. Upon addition of triphenyl‐phosphine the linear dimer becomes the main product. In the trimerization the actual catalyst is a C12 H18Pd2OAc2 complex, formed from π‐allylpalladium acetate via (C7H11PdOAc)2 by displacement of the C7 fragments by three butadiene molecules. The displacement takes place via hydrogen transfer, which also explains the catalytic activity of the C12H18Pd2OAc2 complex. When methanol is used as solvent, butadiene is converted into octadienyl, dodecatrienyl or hexadecatetraenyl methyl esters, depending on reaction conditions. In this reaction a complex is formed in which butadiene is coordinated to zerovalent palladium. The consequences of the isolation of the various intermediate complexes in relation to the reaction mechanism are discussed.
Silver carbonate, a convenient reagent for preparing C‐nitroso compounds from hydroxylamines
Authors: Maassen J.A. , de Boer Th. J.
Published: September 2010

Silver carbonate, precipitated on Celite, is a convenient reagent for the preparation in yields of 55‐95% of C‐nitroso compounds from hydroxylamines.
The chemistry of small ring compounds 13: Transmethylations between methyl cyclopropanecarboxylate and various nucleophiles in alkaline media
Authors: van Der Maeden F.P.B. , Steinberg H. , de Boer Th. J.
Published: September 2010

The Claisen‐Tischenko reaction of cyclopropanecarbaldehyde with sodium methoxide gives rise to the unusual yield of 10% of its dimethyl acetal via methylation of the hemiacetal anion by methyl cyclopropanecarboxylate, one of the normal Claisen‐Tischenko products.

Similar transmethylations between methyl cyclopropanecarboxylate and a variety of nucleophiles [CH3O⊖, cyclo‐C3H5CH2O⊖, n‐C4H9S⊖ and N(CH3)3] can be effected. With methyl sulfide ion instead of methoxide ion, cyclopropanecarbaldehyde reacts with ring opening and formation of unsaturated aldehydes 9 and 10.
Addition of chlorine to the cyanogen bond IV: Synthesis of diisocyano tetrachloride
Authors: Trompen W. P. , Geevers J. , Hackmann J. Th.
Published: September 2010

A comparative study of some isocyanide dichlorides R‐NCCl2 and their isomeric N‐chloro‐formimidoyl chlorides R‐C(Cl) NCl is described. For this purpose we tried to synthesize N‐cyano‐isocyanide dichloride (III) and diisocyano tetrachloride (tetrachloroformalazine) (IX). Chlorination of S,S′‐dimethyl cyanodithiocarbonimidate (II) did not yield III but the dimeric 2,4‐dichloro‐6‐dichloromethylimino‐s‐triazine (IV) (tetramer of cyanogen chloride). IX was prepared by exhaustive chlorination of tetramethylthioformalazine (VI).
The raman and infrared spectra of solid TeCl4 AND SeCl4
Authors: Ponsioen R. , Stufkens D. J.
Published: September 2010

The Raman and infrared spectra of solid TeCl4 and SeCl4 are presented. On the basis of an ionic formulation (MCl3+ and Cl− ions) an assignment of the stretching frequencies of the MCl3+‐ion (with nearly C3v symmetry) is given. The results of a recently published X‐ray analysis of solid TeCl4 made this assignment more detailed. Only suggestions could be made as to the assignment of the bending frequencies of the cations.
Induced vapour phase chlorination of arenes at about 200°C
Authors: Dorrepaal W. , Louw R.
Published: September 2010

The vapour phase (thermal) reaction of arenes (benzene, chlorobenzene, benzonitrile) with molecular chlorine ‐ setting in at roughly 250° ‐ can be made to occur even below 200° by adding small proportions of CCl3‐SO2‐CCl3 (“S”). Products (chlorinated arenes) and relative rates are highly comparable under both sets of conditions. Depending on inter alia, the concentration of S in the feed, from a few to well over 2000 moles of product per mole of S are formed.

Both modes of reaction are interpreted as radical chain processes, chlorine atoms ‐ and their arene adducts ‐ being intermediates. In the initiated reactions. S is thought to form CCl3 radicals, which lead to chlorine atoms by reaction with Cl2.
The low temperature reaction of diazomethane with 1,3,5‐trinitrobenzene: Nucleophilic aromatic addition VIII
Authors: van Velzen J.C. , Kruk C. , de Boer Th. J.
Published: September 2010

There is a strong temperature effect on the reaction of 1,3,5‐trinitrobenzene with diazomethane. At 0° three methylene groups are introduced and the product is the trinitro derivative I (found earlier).

Below −80°, again three methylene groups are introduced, but the main product is a dinitro compound II, isomeric with I but with strikingly different properties.

The methylene groups in II are incorporated in a seven‐membered ring, a cyclopropane ring and an isoxazoline ring, the latter arising by an unusual participation of one of the nitro groups.

The structural proof of II rests on spectroscopic evidence and specific chemical reactions.
A gas‐chromatographic investigation of the thermodynamics of solutions of some normal and branched alkanes, cyclohexane, benzene and tetrachloromethane in polyisobutylene
Authors: Hammers W.E. , de Ligny C.L.
Published: September 2010

From net retention volumes, measured over a wide range of temperatures, solute molar volumes and solute fugacities, standard partial molar free enthalpies, entropies and enthalpies of mixing at infinite dilution in polyisobutylene solution were calculated over a range of temperatures.

Gas‐chromatography is an unique method in the sense that it gives thermodynamic data at polymer mole fractions near unity whereas conventional methods usually are not capable of giving accurate data for very concentrated polymer solutions.

The residual standard partial molar free enthalpies and entropies and the standard partial molar enthalpies of mixing of the normal and branched alkanes were analysed by the (simplified) Prigogine solution theory. Those of the n‐alkanes, cyclohexane, benzene and tetrachloromethane were discussed in terms of the solution theory of Flory, Orwoll and Vrij.
Alkyl 1,1‐dialkoxy‐alkane‐ and ‐arene‐carboxylates. Part IV 1‐alkoxyalkyl carboxylates
Authors: Scheeren J. W. , Nivard R. J. F.
Published: September 2010

Aldehydes can be converted into 1‐alkoxyalkyl carboxylates under mild conditions by reaction with dialkoxymethyl carboxylates in the presence of carboxylic acids. A mechanism has been proposed to explain the appearance of orthoformate during the reaction, and the accelerating effect of this compound on the formation of 1‐alkoxyalkyl carboxylates.

Thermostable 1‐alkoxyalkyl carboxylates can be prepared also from acetals and carboxylic acids though in low yields.

Higher homologues were obtained from the 1‐alkoxyalkyl acetates by exchange of the acid group in a distillation procedure. In a similar way formates were obtained from butyrates and the formic acid/triethylammonium formate azeotrope.
The difference of the standard chemical potentials of KCl in water and in mixtures of water with ethanol, dioxane and acetone
Authors: Bax D. , Alfenaar M. , de Ligny C. L.
Published: September 2010

The difference of standard chemical potentials of KCl in water and in mixtures of water with ethanol, dioxane and acetone has been determined by means of emf measurements on the cell:

magnified image

An improved cell design was used for these measurements.
Synthesis of optically active eremophilane sesquiterpenoids from sabinene
Authors: van Der Gen A. , van Der Linde L. M. , Witteveen J. G. , Boelens H.
Published: September 2010

An efficient route to optically pure sesquiterpenoids of the nootkatane type is described. Stereoselective Michael‐type addition of (‐)‐3‐methylsabinaketone (9) to trans‐3‐penten‐2‐one is used to create the asymmetric centers at C(4) and C(5) in the tricyclic ketone 12. Practical procedures for the conversion of 12 into (‐)‐α‐vetivone (17) and (‐)‐nootkatone (18) are presented.
The dielectric properties of some simple triglycerides
Authors: Ras A.M. , Bordewijk P.
Published: September 2010

Values of ϵ′ and ϵ″ were determined for glycerol triacetate, tripropionate, and tributyrate in the frequency ranges 120 Hz to 100 kHz and 100 MHz to 9 GHz. The temperature‐dependence of the static dielectric constant indicates that the conformation of the molecules changes with the temperature. This conclusion is corroborated by the fact that for the triacetate and the tripropionate the distribution of relaxation times becomes broader with increasing temperature.
Synthesis of acetals using molecular sieves
Authors: Roelofsen D.P. , Wils E.R.J. , van Bekkum H.
Published: September 2010

Acetals can be prepared in high yield from the corresponding aldehydes or ketones and alcohols using molecular sieves to shift the equilibria by adsorption of the water formed. Examples include acetals of acetone, cyclohexanone, iso‐butyraldehyde, and benzaldehyde.

Two batch techniques have been applied using the molecular sieve suspended in the reaction mixture at 0° or room temperature.

The first method involves the use of dual‐function proton‐exchanged molecular sieves type Zeolon 500, AW 500, or mordenite. The outer surface of the sieve catalyzes the acetal formation whereas the inner surface selectively adsorbs the water formed.

According to the second procedure molecular sieve and catalyst p‐toluene‐sulfonic acid are added to the reaction mixture. In this case proton exchange between catalyst and sieve occurs which appeared to be fast with the molecular sieves types KA and NaA, much less pronounced with the types CaA, Zeolon 500, and AW 500. All these sieves however can be used because of the high rate of acetal formation. With KA and CaA essentially quantitative conversions are obtained within a few minutes.
Deazapurine derivatives. VII: Synthesis of substituted imidazo‐ and triazolo‐pyridines
Authors: de Roos K. B. , Salemink C. A.
Published: September 2010

The syntheses of several 7‐substituted imidazo[4,5‐b]pyridines (6‐substituted 1‐deazapurines) and of 7‐substitutedvic‐triazolo[4,5‐b]pyridines (6‐substituted 1‐deaza‐8‐azapurines) are described. A few 6‐substituted 3‐deazapurines and 3‐deaza‐8‐azapurines were also synthesized.

Finally the results of an investigation on the effect of the deazapurines upon the growth ofS. faecalisare described.
Nuclear magnetic resonance contact shifts and delocalization mechanisms in Ni(II)‐dioxo complexes
Authors: Pijpers F. W. , Smeets H. E. , Beentjes L. B.
Published: September 2010

The temperature dependence of the proton NMR‐spectra of bis(1,3‐diphenyl‐1,3‐propanedionato)Ni(II) and of bis(1,3‐di‐p‐tolyl‐1,3‐propanedionato)Ni(II) has been determined.

We have interpreted the results using a model with two unpaired electrons per molecule. We conclude that the contact shifts of the various proton resonance signals result from delocalized unpaired electrons in the σ as well as the π system of the ligands.
Decyanation of cyanomethyl derivatives of aza‐aromatic compounds
Authors: van der Plas H. C. , Jongejan H.
Published: September 2010

2‐ and 4‐Cyanomethylpyridine, 1‐methyl‐ and 1‐benzyl‐2‐cyanomethylimidazole and 3‐cyanomethyl‐1,2,4‐triazole lose the cyano group on reaction with aqueous hydrazine at about 200°, yielding α‐ and γ‐picoline, 1,2‐dimethyl‐ and 1‐benzyl‐2‐methylimidazole and 3‐methyl‐1,2,4‐triazole, respectively. A mechanism is discussed.
Constantes ρ de Hammett dans les Reactions de Formation D'Oximes et de Combinaisons Bisulfitiques
Authors: Geneste P. , Lamaty G. , Roque J. P.
Published: September 2010

The Hammett reaction constant ρ has been measured for the addition reactions of NH2OH and SO−−3 ion to carbonyl compounds; the slopes of the best straigt lines of the log k, σ correlation fonctions are respectively: 0.32 and 1.12. These values are used to. draw conclusions concerning the structure of the transition state and its position along the reaction coordinate; they are consistent with a ‘reactant like’ transition state.
Chemistry of small ring compounds Part 15: The kinetics of the Cannizzaro reaction of cyclopropanecarbaldehyde
Authors: van der Maeden F. P. B. , Steinberg H. , de Boer Th. J.
Published: September 2010

In aqueous sodium hydroxide, cyclopropanecarbaldehyde 1 disproportionates exclusively into cyclopropylmethanol 2 and cyclopropanecarboxylic acid 3 (Cannizzaro reaction). The reaction is second order in aldehyde and second order in base and shows a small positive salt effect. These results and the absence of deuterium incorporation in the alcohol 2, when the reaction is carried out in D2O, have been rationalized in scheme 1.

The enthalpy and entropy of activation are found to be ΔH ≠ = 11.7 ± 0.6 kcal/mole and ΔS ≠ = −17.5 ± 1.0 e.u. (74°). The results of the crossed Cannizzaro reaction between benzaldehyde and cyclopropanecarbaldehyde suggests that cyclopropyl is a better electron‐donating group than phenyl.
Some remarks concerning the interpretation of shifts in carbon(1s) electron binding energies
Authors: Bus J. , de Jong S.
Published: September 2010

The carbon (1s) electron binding energies (Eb) of methyl acetate (CH3:285.6, CO: 289.5 and OCH3: 286.5 eV) correlate well with CNDO/2‐charges (slope 5.6 eV/unit charge), with Pauling charges (slope 5.1) and with Extended Hückel charges (slope 2.4).

If the Eb‐values are corrected for molecular potentials (V), again good correlations are found (slope 22.0, 20.9 and 18.6 resp.). Because it did not make much difference which method was used for calculating charges (q), tests have been made to establish whether charge calculations based on electronegativities could be used for a large series of C(1s) binding energies. For adjacent charges of equal signs, a correction was introduced and it was also found that Jolly's (or Johnson's) electronegativity values gave better results than the Pauling values.

Resonably good correlations were obtained for the function Eb = α + βq + κV with κ = 0, κ = 1 and κ ≠ 0. Introduction of a γq2 term did not improve the correlation. The best fit was obtained with Eb = 285.3 + 11.75 q + 0.48 V ± 0.8 (st. dev.).
NMR and X‐ray diffraction spectra of two hexachloro addition products of biphenyl (E and A); the molecular structures of E and A; the crystal structure of E
Authors: de Mey Catharina A. , de Kok A. J. , Lugtenburg J. , Romers C.
Published: September 2010

Crystals of the title compounds are monoclinic. The lattice constants of the first compound (E) are: a = 16.33, b = 6.48, c = 6.96 Å and β = 91.03° at 20°C. Its space group is P21 and Z = 2. The configuration follows from a three‐dimensional X‐ray analysis and turns out to be 1e,2e,3e,4e,5e,6e‐hexachloro‐1a‐phenylcyclohexane. The conformation is described by means of Newman projections. The sum of C‐Cl vectors is not zero and results in a calculated electric moment of 1.06 D, the experimental value being 1.65 D.

The lattice constants of the second compound (A) are: a = 20.0, b = 10.8, c = 15.2 Å and β = 112.4° at 20°C. The space group is P21/c and Z = 8.

The interpretation of the NMR spectrum of E agrees quite well with the X‐ray analysis. The configuration of A was established by combined NMR (100 and 220 MHz) and 13CNMR techniques, its molecular structure being 1a,2a,3e,4e,5e,6e‐hexachloro‐1e‐phenylcyclohexane.
Activity coefficients of single ions III: The difference between the standard chemical potentials of single ions in methanol and methanol‐water mixtures and in water at 25°C, and some related quantities
Authors: Bax D. , de Ligny C. L. , Alfenaar M.
Published: September 2010

The method described by De Ligny et al. for the estimation of activity coefficients of single ions, which originated from ideas of Alfenaar and De Ligny, Buckingham, Halliwell and Nyburg and Muirhead‐Gould and Laidler, has been improved further.

The modified method was applied successfully to the transfer of ions from water to methanol and methanol‐water mixtures.

A similar method was used to estimate the standard partial molar enthalpy of transfer ΔH° of single ions, and from these data values for the standard partial molar entropy of transfer ΔS° were obtained.

The differences between the standard real potentials of the chloride ion in methanol and methanol‐water mixtures, and in water have been determined by Case and Parsons. From these data, the corresponding differences for the standard chemical potentials and the surface potential of water, the surface potentials of methanol and methanol‐water mixtures, were determined.
Chemistry of acetylenic ethers 97: Claisen‐rearrangement of 1‐alkynyl allenyl sulfides synthesis of acetylenic thioamides and derivatives of thiophene
Authors: Meijer J. , Brandsma L.
Published: September 2010

1‐Alkynyl allenyl sulfides H2C=C=CHSC≡ CR1 (R1 = CH3, C2H5), prepared from alkynethiolates LiSC≡CR1 and propargyl bromide in liquid ammonia, rearrange at room temperature to thioketenes HC≡CCH2C(R1)=C=S. These can be trapped by amines R22NH (R2 = C2H5, C3H7) to give the acetylenic thioamides H≡CCH2CH(R1)C(=S)NR22 in fair to good yields. Potassium tert‐butoxide in liquid ammonia causes cyclization of the thioamides to 2‐dialkylamino‐3,5‐dialkylthiophenes. The same thiophenes are obtained by simply heating the thioamides in hexamethylphosphoric triamide.
The nematocidal activity of 1,2‐DI(2‐thienyl)ethenes: Mode of action
Authors: Drenth W. , Handelé M. J.
Published: September 2010

Nematocidal activity of 1,2‐di(2‐thienyl)ethenes involves electron acceptance by these molecules.
Electrocyclic reactions in a cyclohexadiene‐hexatriene system
Authors: Gaasbeek C. J. , Hogeveen H. , Volger H. C.
Published: September 2010

In a consecutive series of stereospecific reactions under alternately thermal and photochemical conditions cis‐1,2,3,4,5,6‐hexamethylcyclohexa‐1,3‐diene I, 3,4,5,6‐tetramethyl‐(Z,Z,E)‐octa‐2,4,6‐triene II, transf‐1,2,3,4,5,6‐hexamethylcyclohexa‐1,3‐diene III and 3,4,5,6‐tetramethyl‐(Z,Z,Z)‐octa‐2,4,6‐triene IV have been synthesized from 1,2,3,4,5‐endo,6‐endo‐hexamethylbicyclo[2.2.0] hex‐2‐ene as the starting material. Thermal ring closure of the triene IV did not give the cis‐diene I, but, among other products, the trans‐diene III. An intermediate product in this reaction is 3,4,5,6‐tetramethyl‐(Z,Z)‐octa‐1,3,5‐triene V, formed via a [1,7a] H shift.

The structure of compound IV has been assigned on the basis of chemical and spectroscopic (13C and 220 MHz 1H NMR) data.

Cis‐diene I can, at room temperature, be converted direct into trans‐diene III under the influence of hydrochloric acid.
Asymmetric synthesis of optically active 6‐thiaestrogens
Authors: Könst W. M. B. , Speckamp W. N. , Houwen H. O. , Huisman H. O.
Published: September 2010

(13S,17S)‐6‐Thiaestrogens have been synthesized by asymmetric conversion of the corresponding 8,14‐seco‐steroid.
Pyrazoles and imidazoles as ligands. Part XI: Mössbauer spectra of tetragonal pyrazole complexes of Fe(II)
Authors: Reedijk J. , Engelfriet D. W.
Published: September 2010

Compounds of the type Fe(ligand)4(anion)2, with pyrazole and 5‐methylpyrazole as ligands, and I−, Br−, Cl−, NO−3 and NCS− as anions, have been investigated by Mössbauer spectroscopy at 300 and 90° K.

The observed centre shifts of the compounds are in the 1.29‐1.33 mm/s range at room temperature and 1.42‐1.45 mm/s range at liquid nitrogen temperatures, and fall in the lower range of the region found for Fe(II) in the high‐spin state. The observed quadrupole splittings were found to be largely dependent upon the particular combination of ligand and anion, and, for some compounds also upon the temperature.

Comparison of the quadrupole splittings with previously obtained ligandfield parameters confirms the 5Eg ground state for the Fe(II) ion, and agrees with a tetragonal symmetry for the species FeL4A2. In addition, small rhombic distortions were found to be present for the compounds with the ligand 5‐methylpyrazole. A 5B2g ground state is proposed for Fe(pyrazole)4(NCS)2.

In all compounds the splitting of the octahedral 5T2g state is quite large, placing the 5B2g level about 2‐3 kK above the 5Eg state.

The lattice contribution to the quadrupole splitting (0.8‐1.6 mm/s for most compounds) is shown to be much larger than previously assumed for high‐spin Fe(II).
Gas phase reaction of ethene with carbonyl sulfide and carbon disulfide in a silent electrical discharge
Authors: van Drumpt J. D.
Published: September 2010

The gas phase reaction between ethene and COS or CS2 in a silent electrical discharge at atmospheric pressure is described. In both cases S(3P) and S(1D) atoms are formed, which react with ethene to give epithioethane and ethenethiol besides minor amounts of polymer.
Stereoselectivity in the complex formation of penicillamine with nickel(II)
Authors: Ritsma J. H. , Jellinek F.
Published: September 2010

Stability constants of nickel(II) and zinc complexes of optically active and racemic cysteine and penicillamine (dianion: penam) in aqueous solution have been determined. For the complex Ni(penam)22− a significant stereoselective effect in favour of the racemic mixture (MLL + MDD) was observed, the meso complex MDL having an excess Gibbs energy of 0.5‐0.6 kcal/mole (2.1‐2.5 kJ/mole) relative to the racemic mixture. For Zn(penam)22− a small effect, on the edge of significance, in favour of the meso complex MDL was found; no stereoselectivity was observed for the cysteine complexes.
Activity coefficients of single ions IV.: The difference between the standard chemical potentials of single ions in ethanol and ethanol‐water mixtures and in water at 25°, and some related quantities
Authors: Bax D. , de Ligny C. L. , Remijnse A. G.
Published: September 2010

A method for the estimation of standard chemical potential differences (Δμ°) of single ions for the transfer from one solvent to another, derived previously, is applied to the transfer of ions from water to ethanol and ethanol‐water mixtures.

A similar method is used to estimate the standard partial molar enthalpy of transfer, ΔH° of single ions, and from these data values for the standard partial entropy of transfer, ΔS° are obtained.

The difference between the standard real potentials of the chloride ion in ethanol and in water has been determined by Case and Parsons. From these data, the corresponding value of Δμ° and the surface potential of water, the surface potential of ethanol is determined.
Kinetics and mechanism of urethane formation in DMF: The reaction of 4, 4′‐di‐isocyanatodiphenylmethane with alcohols
Authors: Borkent G. , van Aartsen J. J.
Published: September 2010

The rate constants of reactions between 4, 4′‐di‐isocyanato‐diphenylmethane (MDI) and alcohols in N, N‐dimethylformamide (DMF) have been determined by an UV‐spectroscopic method. On the basis of the kinetics observed and the values of the activation parameters ΔS ≠ and ΔH ≠, a proposal is made for a mechanism with a four‐centre transition state. The rate constants for the reaction of several alcohols with MDI in DMF are correlated with the extended Taft equation:
equation image

(Ecs = corrected steric substituent constant according to Hancock).
The synthesis of 14α, 17α‐alkylidenedioxy‐9α‐and 9β‐estrane derivatives. Stereospecific reduction of Δ9(11)‐steroids
Authors: Kooreman H. J. , van der Sijde D. , Marx A. F.
Published: September 2010

Catalytic hydrogenation of the 9(11)‐double bond of 3, 14α, 17α‐trihydroxy‐19‐nor‐1, 3, 5(10), 9(11)‐pregnatetraen‐20‐one (1a) furnished a mixture of the 9α‐ and 9β‐stereoisomers.

In the case of the 14α, 17α‐ethylidenedioxy‐derivatives 4a and 4b the 9β‐isomers were obtained almost exclusively.

Reduction of 14α, 17α‐ethylidenedioxy‐3‐methoxy‐1, 3, 5(10), 9(11)‐pregnatetraen‐20‐one (4b) with sodium in liquid ammonia gave the steroisomeric 9α‐compounds (5b).

The stereochemistry of the compounds was determined by NMR‐spectroscopy.
Formation and PMR spectra of arene dipositive ions
Authors: Brouwer D. M. , van Doorn J. A.
Published: September 2010

Perylene, naphthacene, anthracene and some substituted anthracenes are oxidized to the dipositive ions by SbF5 (neat or in SO2CIF). In FSO3H‐SbF5 dication formation takes only place with the easily oxidizable arenes perylene and naphthacene. The dication of anthracene has also been obtained by bromide abstraction from 9, 10‐dibromo‐9, 10‐dihydroanthracene. The PMR spectra of the dications are reported. Like in the dianions, the sum of the charge‐induced shifts varies considerably from one arene to the other.
Activation and transfer of oxygen VII: Synthesis and spontaneous oxidation of some 1, 8‐blocked tetrahydropteridines
Authors: Mager H. I. X. , Berends W.
Published: September 2010

Some tetrahydropteridines carrying methyl substituents at the N(1)‐, N(3)‐and N(8)‐positions were synthesized and subjected to autoxidation (V and XIII). A spontaneous oxidative contraction of the pyrimidine ring occurred in aqueous solution (XIII + O2 → XXI). This result was in agreement with a theory which has already been put forward.

5‐Acetyl‐tetrahydropteridines were required for synthetic purposes. They could not generally be prepared by reduction of pteridines with zinc/acetic acid/acetic anhydride. A contraction of the pyrazine ring occurred in the attempted reductive acetylation of 1, 3, 6, 7‐tetramethylpteri‐2, 4‐dione (IX). The product was identified as 1, 3, 8‐trimethyl‐2, 6‐dioxopurine (XIV = 8‐methyl‐theophylline). Starting from 1, 3‐dimethylpteri‐2, 4‐dione the same procedure led to a mixture of two dimeric acetyl‐tetrahydropteridine derivatives.
On the mechanism of the amination of 4‐halogeno‐6‐phenylpyrimidines with potassium amide in liquid ammonia
Authors: de Valk J. , van der Plas H. C.
Published: September 2010

The synthesis of the 4‐chloro‐, 4‐iodo‐ and 4‐fluoro derivatives of 6‐phenyl‐[1(3)‐15N]pyrimidine is described. The amination of 4‐chloro‐ and 4‐fluoro–6‐phenyl‐[1(3)‐15N]pyrimidine with potassium amide in liquid ammonia at −75° occurs to a great extent (93% ± 5% and 73% ± 5%, respectively) according to the ANRORC‐mechanism. In the conversion of 4‐iodo‐6‐phenyl‐pyrimidine into the corresponding 4‐amino compound the ANRORC‐mechanism occurs to the extent of about 10% only; evidence has been put forward that in this conversion an EA‐mechanism is mainly operative.
Tetrakis(t‐butyl isocyanide)nickel(II) perchlorate
Authors: Stephany R. W. , Drenth W.
Published: September 2010

Ni(CN‐t‐C4H9)4(H2O)2(ClO4)2 has been prepared and reversibly converted to Ni(CN‐t‐C4H9)4(ClO4)2. Infrared, electronic, proton magnetic resonance and some X‐ray data are provided.
Studies on vitamin D and related compounds XXII: New reactions and products in vitamin D3 photochemistry
Authors: Bakker S. A. , Lugtenburg J. , Havinga E.
Published: September 2010

From the mixtures resulting from U.V. irradiation (λ > 250 nm) of solutions of vitamin D3 in ethanol four novel products could be isolated besides suprasterols3 I and II. The NMR and other data suggest that two of the new compounds found are stereoisomeric vinylallene derivatives, whereas the two others may represent cyclobutene derivatives (Fig. 3). The six photoproducts of vitamin D3 correspond to what would be expected from a 1,3,5‐hexatriene occurring in a s‐trans‐Δ3‐cis‐s‐cis conformation.
Aromatic lead(IV) compounds. III: The plumbylation of aromatic ethers in the presence of halogen‐substituted acetic acids: (Preliminary communication)
Authors: de Vos D. , Spierenburg J. , Wolters J.
Published: September 2010

The widened scope of the improved method of plumbylation of aromatic ethers has made novel aryllead(IV) compounds accessible.
Mannich‐type condensation reactions of sulfinic acids with aldehydes and nitrogen bases: Part. VI. The use of ureas, thioureas and thiobenzamide
Authors: Meijer H. , Tel R. M. , Strating J. , Engberts J. B. F. N.
Published: September 2010

Urea, thiourea and some N′‐alkyl(di)substituted ureas and thioureas were found to react as the amine component in Mannich‐type condensation reactions with p‐toluene‐ or phenylmethane‐sulfinic acid and aldehydes. Mono‐ or di‐alkylation products are formed in good yields depending on the N′‐ and N′‐substituents in the substrate, while N,N,N′‐trimethylurea or ‐thiourea failed to react. N′‐Hydroxy‐N′‐phenylthiourea is alkylated on the N′‐atom bearing the OH‐substituent as demonstrated by the ESR spectrum of the thioacyl nitroxide derived from the condensation product. Thiobenzamide, in contrast with thioacetamide, also condensed with p‐toluenesulfinic acid and formaldehyde or N′‐butyraldehyde. With benzaldehyde, however, Mannich‐type condensation did not occur and 3,5‐diphenyl‐1,2,4‐thiadiazole was isolated instead.

The NMR spectra of several urea and thiourea condensation products provided evidence for hindered internal rotation in the urea and thiourea function and some ΔG≠ values for the exchange process were estimated. Intramolecular shielding effects were observed in the NMR spectrum of 4c and 4f indicating the occurrence of folded conformations.
Isolation of purine oligonucleotides after hydrazinolysis of deoxyribonucleic acid
Authors: Havelaar K. J. , de Waard A.
Published: September 2010

A modified version of the classical degradation of deoxyribonucleic acid by hydrazine has been used to obtain undamaged purine‐deoxyribo oligonucleotides. This method exploits hydraziniumchloride as a reagent capable of β‐elimination of the phosphate ester group from C(3) of a deoxyribose originally carrying a pyrimidine. Alkaline hydrolysis completes the required scission of the sugar‐phosphate backbone and removes remnants of the pyrimidine skeleton still attached to some deoxyribose residues. A novel type of reaction of alkaline phosphatase from E. coli was used with advantage to free the purine‐isostychs from substitution products of deoxyribose originally carrying a pyrimidine. The resulting purine‐isostychs have been separated and characterized.
Synthesis of human growth hormone sequences. Solid‐phase synthesis of protected 1‐10 and 6‐10 HGH
Authors: de Leer E. W. B. , Beyerman H. C.
Published: September 2010

The solid‐phase synthesis of the fully protected N‐terminal decapeptide sequence of human growth hormone, Boc‐Phe‐Pro‐Thr(ZTF)‐Ile‐Pro‐Leu‐Ser(Bzl)‐Arg‐(NO2)‐Leu‐Phe‐OMe, and the sequence 6‐10, Boc‐Leu‐Ser(Bzl)‐Arg(NO2)‐Leu‐Phe‐OMe, is described. The synthesis of the decapeptide was carried out twice, once with Boc‐amino acid couplings only, and once with dipeptide couplings of Boc‐Ile‐Pro and Boc‐Phe‐Pro. The products were purified by gel chromatography; the product obtained by the first method then still contained an impurity.
Investigation of 90° and 180° superexchange interactions of Ni2+ in MgO by means of magnetic susceptibility methods
Authors: van Leeuwen G. C. M. , van Driel J. C.
Published: September 2010

Magnetic susceptibility measurements in the temperature range of 4‐300°K have been performed on different NixMg1−xO samples with x ranging from 0.0068 to 0.0465. Typical temperature dependent deviations from the single‐ionsusceptibility were observed for all samples. These deviations have been explained by taking into account the effect of both 90° and 180° superexchange interactions. Assuming a random distribution of Ni2+ ions over the Mg2+ sites, the contributions from the various bi‐ and tri‐nuclear clusters to the total susceptibility have been found to check with experiment for J(90°)/k = 2.3 ± 0.2°K and J(180°)/k = 150 ± 10°K.
Synthesis of the pyrroline analogue of nigrifactin: A new oxidation reaction with lead tetra‐acetate
Authors: de Koning H. , Springer‐Fidder A. , Moolenaar M. J. , Huisman H. O.
Published: September 2010

The pyrroline analogue of nigrifactin ‐ 2‐(1,3,5‐heptatrienyl)‐1‐pyrroline (2) ‐ has been synthesized. A key‐step is oxidation of 2‐hydroxymethyl‐1‐tritylpiperidine (6) with lead tetra‐acetate in presence of pyridine, leading to the formation of 2‐diacetoxymethyl‐1‐tritylpyrrolidine (7). The mechanism of this oxidation reaction is discussed.
Synthesis of 2trans‐alkene‐mono‐and ‐poly‐ynoic acids with a triple bond in the 5‐position and their hydrogenation. A new synthesis of arachidonic acid
Authors: Heslinga L. , Pabon H. J. J. , van Dorp D. A.
Published: September 2010

27Trans‐alkenoic, 2trans‐alkenemonoynoic and 2trans‐alkenepolyynoic acids with the first triple bond in the 5‐position could be obtained in high yield by coupling 1‐alkyl‐ and 1‐mono‐ or ‐poly‐ynylmagnesium bromides with 4‐bromocrotonic acid in tetrahydrofuran at low temperature.

By hydrogenation in the presence of Lindlar's catalyst, cis polyenoic acids with a 2trans double bond have been synthesized. On continued hydrogenation, the 2trans double bond can be removed selectively. This new method has been applied to the synthesis of 2trans,5cis,8cis,11cis,14cis‐eicosapentaenoic acid and its hydrogenation to 5cis,8cis,11cis,14cis‐eicosatetraenoic acid (arachidonic acid).
Ring transformations in reactions of heterocyclic halogeno compounds with nucleophiles (XXVIII) A study of the mechanism of transformation of chloropyrazine into 2‐cyanoimidazole using 14C‐ and 15N‐labelling
Authors: Lont P. J. , van der Plas H. C.
Published: September 2010

The mechanism of the conversion of chloropyrazine into 2‐cyanoimidazole by the action of potassium amide in liquid ammonia has been investigated. Using 2‐chloro[4′ 15N]pyrazine and 2‐chloro[2′ 14C]pyrazine it has been shown that ring contraction occurs by a nucleophilic attack of the amide ion at C(3), followed by fission of the C(3)‐N(4) bond.
ESCA‐Investigations of thallium(I) salts of β‐dicarbonyl compounds
Authors: Kolind‐Andersen H. , Lawesson S.‐O. , Larsson R.
Published: September 2010

The binding energies of the Tl(4f5/2) electrons in various thallium(I) salts of β‐dicarbonyl compounds have been measured. The mean value is considered as the “group shift”. The influence of the substituents on the binding energy of the core electrons in the thallium atom is of second order. No systematic influence on the binding energies of the Tl(4f5/2) electrons is found from the substituents on the heterocyclic six‐membered ring, formed by the ligand and the metal atom.
Nigrifactin analogues: Synthesis of some hetero‐aromatic polyenes via the Horner reaction
Authors: de Koning H. , Mallo G. N. , Springer‐Fidder A. , Subramanian‐Erhart K. E. C. , Huisman H. O.
Published: September 2010

Some all‐trans 1,3,5‐heptatrienyl and 6‐ethoxycarbonyl‐1,3,5‐hexatrienyl substituted heterocyclic compounds have been synthesized, employing Horner reactions of heterocyclic aldehydes or heterocyclic methylphosphonates.
Hydride transfer reactions: II. Hydride transfer from alkanes to methyloxocarbonium ion
Authors: Brouwer D. M. , Kiffen A. A.
Published: September 2010

The hydride transfer from some alkanes to acetyl cation (methyloxocarbonium ion, 1), which yields acetaldehyde and alkylcarbonium ions as the primary products, has been investigated in HF solution. In HFBF3 the reaction of isobutane with 1 affords protonated mesityl oxide and protonated ethyl acetate as the first observable products. The former ion arises from acetylation of isobutene and the latter through rapid abstraction of hydride from isobutane by protonated acetaldehyde, followed by acetylation of the ethanol thus formed. Similar results were obtained with isopentane and methylcyclohexane. In 9:1 HFSbF5, reaction of 1 with isobutane gives t‐butyl ion and protonated ethanol. The rates are the same in HFSbF5 and HFBF3 (k ∼ 10−4M−1s−1 at 20°C), which shows that the hydride transfer to oxocarbonium carbon is not assisted by protonation of the incipient aldehyde. Hydride abstraction by 1 from n‐butane is slower than that from isobutane by a factor of at least 103.

The present results are compared with those obtained in the reactions of (cyclo)alkanes with acetyl chloride‐aluminium chloride.
The formation of a 1‐methyl‐2‐(4‐pyrimidinyl)hydrazine from a di‐4‐pyrimidinyl carbonate and methylhydrazine
Authors: Dekker W. H.
Published: September 2010

The reaction between methylhydrazine and bis[2‐(dimethylamino)‐5,6‐dimethyl‐4‐pyrimidinyl] carbonate leads to 1‐[2‐(dimethylamino)‐5,6‐dimethyl‐4‐pyrimidinyl]‐2‐methylhydrazine instead of the expected 2‐(dimethylamino)‐5,6‐dimethyl‐4‐pyrimidinyl 2‐methylcarbazate.
Synthesis and reactions of 3‐OXO‐2H‐furan derivatives
Authors: de Rijke D. , Boelens H.
Published: September 2010

2‐Alkyl‐4‐ethoxycarbonyl‐5‐methyl‐3‐oxo‐2H‐furans (I, R′ = Et) can be prepared at − 20° from ethyl acetoacetate and α‐bromo carboxylic acid chlorides. The furans do not enolize to hydroxyfurans, but behave essentially as unsaturated ketones towards various nucleophiles. With potassium hydroxide, ring opening and closure leads ultimately to 3‐acetyl‐5‐alkyl‐4‐hydroxy‐2‐oxo‐5H‐furans (II); with sodium methoxide the overall process is one of decarboxylation while oxidative decarboxylation with hydrogen peroxide in an alkaline medium yields 2‐alkyl‐4‐hydroxy‐5‐methyl‐3‐oxo‐2H‐furans (IV). As illustrated in Scheme 1 all three processes are thought to be initiated by the addition of a nucleophile (HO−, CH3O−, HOO−) on the activated double bond in the furans.
Raman and IR spectra and structures of POBr3 and PSBr3 in the solid state
Authors: Olie K. , Stufkens D. J.
Published: September 2010

Raman and infrared spectra of solid POBr3 and PSBr3 are presented and assigned. The results are discussed in terms of intermolecular interactions.
Chemistry of acetylenic ethers 100: Dialkyl(methylthioethynyl)phosphine oxides; synthesis and reactions
Authors: Hagens W. , Bos H. J. T. , Arens J. F.
Published: September 2010

The directiospecificity and stereochemistry of the addition of nucleophiles (Me2NH, MeS⊖ and MeO⊖), of electrophiles (HCl and H3O⊕) and of the free radical C2H5S to Me2P(O)CCSMe and Et2P(O)CCSMe have been studied. The structural assignment of the adducts was based on PMR (Table II); coupling constants 2JPH in R2P(O)CHCYZ decrease with increasing electronegativity of Y and Z.
Bicyclic γ‐lactone formation in the Reformatsky reaction with 2‐substituted cyclopentanones
Authors: Ward J.P.
Published: September 2010

Bicyclic γ‐lactones were found among the products of reaction of two 2‐substituted cyclopentanones with bromoacetic esters and zinc (Reformatsky). The intermediate β‐hydroxy‐acid obtained from 2‐pentylcyclopentanone with zinc and tert‐butyl bromoacetate in benzene was converted to 4‐pentyl‐3,4‐trimethylene‐4‐butanolide in 67% yield. The preparation of 1‐(2‐carboxyethyl)‐2‐(7‐carboxyheptyl)cyclopentene is described.
Kinetics of water‐ammonia exchange in the series of aquaamminecobalt(III) complexes: II. Reactivity difference between cis‐ and trans‐aquahydroxotetraamminecobalt(III) ions in the reaction with ammonia
Authors: Bohte E.G.A.M. , Balt S.
Published: September 2010

The reactions of dihydroxotetraamminecobalt(III) perchlorate have been studied in an aqueous solution of 8M‐ammonia containing 1.80M‐ammonium perchlorate, at 25°. Under these conditions the isomerization and the uptake of ammonia occur at comparable rates. From the analysis of the absorbance as a function of time it followed that cis and trans ions react with ammonia at nearly equal rates. On the basis of this information the steric factor in the labilization of Co(III) ligand bonds by a coordinated hydroxo group is discussed.
New macrocyclic compounds from the secretions of the civet cat and the musk rat
Authors: van Dorp D.A. , Klok R. , Nugteren D.H.
Published: September 2010

The odoriferous glands of the civet cat and the musk rat contain not only the limited number of macrocyclic components described in the classical literature, such as civetone (9cis‐cycloheptadecenone), but a whole spectrum of saturated and unsaturated cyclic ketones and alcohols. In the musk rat, peculiar compounds containing conjugated and/or triple bonds were found; the unsaturation was located here exclusively at the 5 and/or 7 position. The macrocyclic alcohols were always esterified with long chain fatty acids. The absolute configuration of the dextrorotatory unsaturated alcohols was established as S. Some of the new compounds have been made in quantity by total organic synthesis, viz. 5‐cyclopentadecynone, 5cis‐cyclopentadecenone, 5‐cycloheptadecynone, 5cis‐cycloheptadecenone and 9cis‐cyclononadecenone.
A study of π‐conjugation in Chichibabin's ‐ and Schlenk's ‐ like hydrocarbons with ESR: Part i
Authors: Kooistra By C. , van Dijk J. M. F. , van Lier P. M. , Buck H. M.
Published: September 2010

Analysis of the ESR spectrum of the radical cation, derived from p, p′‐bis‐{phenyl(triphenylphosphorylidene)methyl}biphenyl reveals that spin density is found at both 31P nuclei. Zero spin density is indicated for the outer phenyl rings. In the radical cation, derived from the corresponding m,m′‐isomer the spin density is delocalized over one half of the molecule and interaction is found with only one phosphorus atom. In this system the spin density in the outside ring exceeds that in the biphenyl ring. The localization of the odd electron on one half of the molecule must be caused by a strong Jahn‐Teller effect.

The assignment of the hyperfine coupling constants was based on spin density calculations according to the Unrestricted Hartree‐Fock (UHF) method. From these calculations we also obtained an indication of the geometry of the radicals.

The synthesis of these compounds is reported.
PMR‐spectra of some diastereoisomeric ionol isomers in the presence of EUIII‐2,2,6,6‐tetramethylheptadionate
Authors: Kruk C. , Roof A. A. M. , van Wageningen A. , Cerfontain H.
Published: September 2010

PMR‐spectra of diastereoisomers containing two chiral centres can be elucidated by complexation with the EuIII‐heptadionate shift reagent, as is illustrated for the two pairs of diastereoisomers of both (E)‐α‐ionol (I) and the bicyclic ionol II.
Vinyl orthoformates and vinyl acetals. Part iii: The reactions of alkenyl acetals and l‐alkenyloxyalkyl carboxylates with carboxylic acids
Authors: van Melick J. E. W. , Posno T. , Scheeren J. W. , Nivard R. J. F.
Published: September 2010

Treatment of alkenyl acetals IV with one equivalent of a carboxylic acid leads to the formation of either addition products, l‐acyloxyalkyl alkenyl acetals VI, or substitution products, l‐alkenyloxyalkyl carboxylates V, dependent upon the structure of the starting compounds. In a similar way the l‐alkenyloxyalkyl carboxylates V give 1,1′‐diacyloxy ethers X, or acylals XI, with a second equivalent of a carboxylic acid. Synthetic applications and tentative reaction schemes of these conversions are given.
Some aspects of the electronic spectra of 1,3‐cyclohexadiene, (E)‐ and (Z)‐1,3,5‐hexatriene
Authors: Minnaard N. G. , Havinga E.
Published: September 2010

The electronic spectra of 1,3‐cyclohexadiene, (Z)‐ and (E)‐1,3,5‐hexatriene were measured and interpreted.

The absorptions between 220 and 280 nm in the gas phase are π → πx‐transitions whereas the second absorption (180‐210 nm) in these compounds is considered to be a Rydberg transition. A weak π → πx‐transition is hidden by the latter absorption in (Z)‐hexatriene. The band in the solution spectrum of cyclohexadiene at 190 nm is thought to correspond to the band at 175 nm in gaseous cyclohexadiene.

Triplet absorption spectra were measured in heavy atom solvents (CH2I2, CHBr3).

A scheme of energy levels is given.
Preparation and ESR of phosphorus spiro compounds. Part II: Stereo‐isomerization of organo‐phosphorus radicals
Authors: Rothuis R. , Freide J. J. H. M. Font , Buck H. M.
Published: September 2010

The synthesis of bis{2,2î‐(5,5î‐dimethoxy)biphenylenephosphonium and bis {2,2′‐(5,5′‐dimethylamino)biphenylene}phosphonium salts is described. The related spiro phosphoranyl radicals II and III, generated by electrochemical reduction, are measured by means of ESR spectroscopy. We observed the same small values of the phosphorus doublet splitting constants as for the bis(2,2′‐biphenylene)phosphoranyl radical I.

In this investigation we found also that the radical obtained by photolysis of bis(2,2′‐biphenylene)phosphorane at −120° appeared to be identical with the radical obtained by electrochemical reduction of the bis(2,2′‐biphenylene)phosphonium ion. Irradiation of the phosphorane which has a trigonal bipyramidal (TBP) configuration results in a cleavage of the equatorial hydrogen atom. The small values of the phosphorus doublet splitting constants give rise to a tetrahedron like (T) configuration in which the unpaired electron is delocalized in the aryl ligands.

We also discuss the associative character of these radicals in dependence on the temperature.
New aspects of the oxygen uptake by Rh(PPh3)3Cl ESR and kinetic results
Authors: van Vugt Barry H. , Koole N. J. , Drenth W. , Kuijpers F. P. J.
Published: September 2010

The rate of oxygenation of Rh(PPh3)3Cl in benzene was measured at 50°C. ESR measurements suggest the presence of a Rh(II)·· O2 species. A mechanism is proposed for this oxygenation and for the subsequent oxidation of one phosphine ligand.
Deazapurine derivatives XII. Investigations on the synthesis of 3‐deazaguanine
Authors: de Bode R. , Salemink C.A.
Published: September 2010

The attempted synthesis of 3‐deazaguanine along two pathways has lead to several new imidazo[4,5‐c]pyridines. 3‐Deazaguanine itself could not be isolated from the preceding 2‐(carbamate acetyl‐)amino‐derivative.
Electrochemical reduction of arenesulfonyl cyanides
Authors: van der Meer D. , Spaans A. , Thijsse H.
Published: September 2010

Benzenesulfonyl cyanide and six para‐substitution products were reduced electrochemically at a dropping mercury cathode, in DMF as solvent. A linear Hammett relation between the half‐wave potentials of the first reduction wave and the σx‐values was observed. This suggests the reduction mechanism being analogous for all molecules studied. The half‐wave potentials could not be correlated with the electron affinities of these molecules, since for all compounds the first reduction wave is irreversible, due to the formation of mercurous intermediates. Performing electrochemical reduction within the ESR cavity spectra were obtained in some cases. For p‐cyanobenzenesulfonyl and p‐nitrobenzenesulfonyl cyanides these ESR spectra could be analysed and were assigned to the p‐cyanobenzenesulfonyl and p‐nitrobenzenesulfonyl dianion radicals, respectively. Prolonged reduction of p‐nitrobenzenesulfonyl cyanide in DMF yields two additional ESR spectra, which could be assigned to the p‐nitrobenzenesulfinyl and p‐nitrobenzenesulfenyl dianions. So the SO2 group is reduced selectively in presence of the NO2 group.
Reductive ring opening of thiazoles
Authors: Hoff S. , Blok A.P.
Published: September 2010

The course of the reductive ring‐opening reactions of 2‐mercapto‐, 2‐hydroxy, 2‐amino‐, 2‐methylamino‐ and 2‐dimethylamino‐4‐methylthiazoles with sodium in liquid ammonia, yielding substituted propenethiolates, has been found to depend on the nature of the hetero substituent. The mechanism of the ring opening is discussed.
Base‐catalysed cyclisation of 2‐alkynyl alkanedithioates (with a note on the preparation of O‐alkyl thioates)
Authors: Vermeer P. , Meijer J. , Bos H. J. T. , Brandsma L.
Published: September 2010

2‐Alkynyl alkanedithioates R1R2CHC(S)‐S‐CH(R3)CCR4 (1, R1 = CH3; R2‐R4 = H or CH3) cyclise on treatment with NaOC2H5 in ethanol to 2,4‐dialkylidene‐1,3‐dithiolanes, 7; if ButOK in 1,2‐dimethoxyethane (DME) is used as a base, the end products are 1,3‐dithiole derivatives 8.
Ring transformations in reactions of heterocyclic halogeno compounds with nucleophiles (XXXIV): Ring contraction of 4‐chloropyrimidine‐1‐oxides into isoxazoles in liquid ammonia
Authors: Peereboom R. , van der Plas H. C. , Koudijs A.
Published: September 2010

In the reaction of 4‐chloro‐6‐R‐pyrimidine‐1‐oxides (R=CH3 or C6H5) with potassium amide in liquid ammonia at −75°C or with liquid ammonia at −33°C besides the formation of the corresponding 4‐aminopyrimidine‐N‐oxides, a ring contraction into 5‐amino‐3‐R‐isoxazoles (R=CH3 or C6H5) has been observed.

A mechanism for the ring contraction reaction is postulated.
Chemistry of alkenethiolates IV: Synthesis and reactions of 1,3‐dithiolane‐2‐thiones and thiazolidine‐2‐thiones
Authors: Hoff S. , Blok A. P.
Published: September 2010

2‐Acetamidoalkenethiolates (1) have been caused to react with several heterocumulenes. Carbon disulfide gave good yields of substituted 4‐acetamido‐1,3‐dithiolane‐2‐thiones (3), which rearranged thermally to thiazoles. Isothiocyanates afforded 4‐acetamidothiazolidine‐2‐thiones (8).