bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chain extension with tert‐butyl lithioacetate
Authors: Bos Wil , Pabon Henk J. J. 
Published: September 2010

AbstractIodides containing methylene‐interrupted triple or double bonds can be chain‐extended in 45‐73% yield by reaction with tert‐butyl lithioacetate in THF/HMPT at −35°C and subsequent acid‐catalyzed thermolysis at 100°C. Alkyl and allyl bromides or iodides give acids in yields of 60 to 89%. In some cases, minor amounts of methyl ketones were found. Alkyl chlorides and alkyl methane‐, benzene‐ or p‐toluenesulphonates are not suitable.
Reactions of organolithium‐diazine adducts and dihydrodiazines with electrophilic reagents
Authors: van der Stoel R. E. , van der Plas H. C. , Jongejan H. , Hoeve L. 
Published: September 2010

AbstractSome organolithium‐diazine adducts and some dihydropyrimidines were treated with electrophilic reagents. Both 4,6‐diphenyl‐1(3)‐lithio‐1,4(3,4)‐dihydropyrimidine and 4,6‐diphenyl‐1,4(3,4)‐dihydropyrimidine were attacked by the electrophilic reagent methyl iodide (methyl chloroformate) at N(3), yielding 4,6‐diphenyl‐3‐methyl(methoxycarbonyl)‐3,4‐dihydropyrimidine. 4,4,6‐Triphenyl‐1,4(3,4)‐dihydropyrimidine upon treatment with methyl iodide gave mainly 3‐methyl‐4,4,6‐triphenyl‐3,4‐dihydropyrimidine. The 3,4‐dihydro structure. of the products was established both spectroscopically and chemically. Reaction of 2‐lithio‐3‐methyl‐2,3‐dihydropyridazine with methyl iodide (methyl chloroformate, tosyl chloride) gave the corresponding 2,3‐dimethyl(2‐methoxycarbonyl‐3‐methyl‐, 2‐tosyl‐3‐methyl)‐2,3‐dihydropyridazine. Reaction of 1‐lithio‐4‐methyl‐ 1,4‐dihydropyridazine with methyl iodide (methyl chloroformate) gave 1,4‐dimethyl(l‐methoxycarbonyl‐4‐methyl)‐1,4‐dihydropyridazine. 1‐Lithio‐2‐phenyl‐1,2‐dihydropyrazine upon treatment with methyl iodide afforded 5‐methyl‐2‐phenylpyrazine. Reaction with carbonyl compounds produced only high‐molecular weight material.
The behaviour of 6‐ and 8‐substituted purines toward potassium amide in liquid ammonia. A new example of tele‐amination
Authors: Kos N. J. , van der Plas H. C. , van Veldhuizen A. 
Published: September 2010

AbstractReaction of 6‐chloro‐ and 6‐(methylthio)purine with potassium amide in liquid ammonia leads to the formation of adenine. When these aminations are carried out with 15N‐labelled potassium amide, the 15N label is found to be present in the amino group, proving that these reactions do not involve opening of the pyrimidine ring. Low temperature 1H‐ and 13C‐NMR spectroscopy of solutions of 6‐chloro‐ and 6‐(methylthio)purine in liquid ammonia, containing potassium amide give no evidence for the presence of an intermediary σ‐adduct. 8‐Chloro‐ and 8‐(methylthio)purine undergo a Tschitschibabin amination at position 6 leading to 8‐chloro‐ and 8‐(methylthio)adenine. In addition 8‐chloropurine gives adenine. Evidence is presented that the formation of this product proceeds via a tele‐amination. 6‐tert‐Butyl‐8‐(methylthio)purine and 8‐aminopurine are found to be unreactive towards potassium amide.
Functionalized enamines XXIX. Solvolytic transformations of 2‐methylisoquinolin‐1‐one dichlorocarbene adduct. Synthesis of benzazepinones
Authors: Soetens H. P. , Pandit U. K. 
Published: September 2010

AbstractDichlorocarbene, generated from base‐catalysed decomposition of chloroform, adds to the double bond of 2‐methylisoquinolin‐1‐one (1), to give the 1:1 adduct (2). The latter adduct reacts with water to give E‐3‐(formylmethylene)‐2‐methylisoindolinone (3a). Refluxing of 2 in alcohols yields alkoxybenzazepin‐1‐ones. Upon heating (of 2) in dimethoxyethane and subsequent reduction with lithium borohydride, 4‐chloro‐2‐methyl‐1H‐2,3‐dihydro‐2‐benzazepinone (10) was obtained as the main product. Mechanisms for the formation of these products are discussed.
C‐Nitroso compounds. Part XXXIV. Reaction of α‐chloronitroso compounds with methyl and phenyl Grignard reagents. A convenient synthesis of α,α‐dialkyl‐N‐methyl and ‐N‐phenyl nitrones
Authors: Schenk C. , Beekes M. L. , van der Drift J. A. M. , de Boer Th. J. 
Published: September 2010

AbstractThe α‐chloronitroso compounds 1a–1f were made to react with methyl and phenyl Grignard reagents. N‐methyl and N‐phenyl substituted ketonitrones 2 and 3 were obtained in 48‐78% yield. The structure of these labile nitrones is based on their spectroscopic properties and on the formation of characteristic 1,3‐cycloadducts with phenylisocyanate.
Synthesis of fragments of human β‐lipotropin, βh‐LPH. Part IV*. The synthesis of shortened peptides related to des‐1‐tyrosine‐γ‐endorphin [β‐LPH‐(62‐77)]
Authors: Greven H. M. , van Nispen J. W. , Bijl W. A. A. J. 
Published: September 2010

AbstractThe synthesis of several peptides related to β‐LPH‐(62–77) but shortened from the N‐terminal end, is described. In these syntheses use has been made of the classical fragment condensation approach.
The use of Lanthanum‐139 NMR in the study of complexation behaviour of (hydroxy) carboxylate anions
Authors: Vijverberg C. A. M. , Peters J. A. , Kieboom A. P. G. , van Bekkum H. 
Published: September 2010

AbstractSeveral La(III)‐(hydroxy) carboxylate complexes in aqueous medium have been studied by means of 139La chemical shift and line‐width measurements.
A new type of base‐induced isomerisation of 1,3‐enynes; the reversal of an enyne system
Authors: Verboom W. , Everhardus R. H. , Zwikker J. W. , Brandsma L. 
Published: September 2010

AbstractA new type of base‐catalysed isomerisation of conjugated enynes leads to the reversed enyne systems. The preparative conversion of 1‐(dialkylamino)‐3‐buten‐1‐ynes (1) into 1‐(dialkylamino)‐1‐buten‐3‐ynes (2) is presented.
NAD(P)H models XV. Reduction of Δ4‐3‐ketosteroids via their iminium salts, by 1,4‐dihydropyridine derivatives
Authors: Case Ronald A. , Pandit Upendra K. 
Published: September 2010

AbstractPyrrolidinium salts derived from a series of 17‐substituted Δ4‐3‐ketosteroids are reduced by 1‐benzyl‐1,4‐dihydronicotinamide (BNAH) and 2,6‐dimethyl‐3,5‐diethoxycarbonyl‐1,4‐dihydropyridine (Hantzsch ester, 1 eq.) to the corresponding isomeric 5α‐ and 5β‐enamines which hydrolyse to the corresponding 3‐ketosteroids. In the case of the Hantzsch ester reduction, proton transfer from the oxidized Hantzsch ester to the enamine results in the formation of iminium salts, which are further reduced to the corresponding ammonium salts. Mechanistic, stereochemical and biochemical implications of the reactions are discussed.
The reactions of hetero‐allenes RN=C=X with phosphine derivatives containing a PH bond
Authors: Thewissen D. H. M. W. , Ambrosius H. P. M. M. 
Published: September 2010

AbstractPhosphine derivatives containing a PH bond can add to the C=N double bond of a hetero‐allene molecule RN=C=X. Ph2PH gives Ph2PC(X)NHR (X = O, S: R = Ph; X = N‐p‐tol: R = p‐tol), cy‐C6H11PH2 gives cy‐C6H11P[C(X)NHPh]2 (X = O, S) And Ph2P(Q)H gives Ph2P(Q)C(X)NHR (Q = O: X = S and R = Ph; Q = S: X = O,S and R = Ph, X = N‐p‐tol and R = N‐p‐tol).The preparation of the new compounds, Ph2PC(N‐p‐tol)NH‐p‐tol, Ph2P(S)C(N‐p‐tol)NH‐p‐tol, Ph2P(O)C(O)NPhC(O)NHPh, cy‐C6H11P[C(S)NHPh]2 and cy‐C6H11P[C(O)NHPh]2, is reported.
The use of the 2,4‐dinitrophenyl group in sugar chemistry re‐examined
Authors: Koeners H. J. , de Kok A. J. , Romers C. , van Boom J. H. 
Published: September 2010

AbstractThe use of the tertiary base 1,4‐diazabicyclo[2,2,2]octane, together with 1‐fluoro‐2,4‐dinitrobenzene in the solvent DMF, proved to be an efficient method for the introduction of the 2,4‐dinitrophenyl (DNP) group at different positions, including the anomeric centre of glucose and galactose. The introduction of the DNP ethers at the anomeric centre leads exclusively to the formation of β‐DNP ethers. The latter derivatives can be easily converted with potassium carbonate in DMF into the α‐DNP ethers. The X‐ray analysis of 2,4‐dinitrophenyl‐2,3,4,6‐tetra‐O‐acetyl‐α‐D‐gluco‐pyranoside is discussed. The DNP group can also be used as a protective group in the synthesis of a disaccharide (i.e. 8) and as a UV probe to monitor (254 nm) and analyse (HPLC) sugar intermediates.
Synthesis of 1,6‐bis(2′‐benzimidazolyl)‐2,5‐dithiahexane and its copper compounds
Authors: Birker P. J. M. W. L. , Helder J. , Reedijk J. 
Published: September 2010

AbstractThe new S2N2‐donor ligand 1,6‐bis (2′‐benzimidazolyl)‐2,5‐dithiahexane, [(C6H4NNHC)CH2SCH2‐]2, has been prepared from 3,6‐dithiaoctanedioic acid and ō‐phenylenediamine. Stable copper (I) and copper (II) complexes are formed. The ESR and optical spectra of the copper (II) complexes are consistent with trigonal bipyramidal coordination of the metal ion.
Preparation and photolysis of deuterium‐labelled rhodopsin analogues
Authors: Fransen M. R. , Palings I. , Lugtenburg J. , Jansen P. A. A. , Groenendijk G. W. T. 
Published: September 2010

AbstractThe compounds 18‐ and 19‐trideutero‐11‐cis‐retinal, > 99% pure, with over 98% and 99% trideuterium incorporation were synthesized together with the corresponding all‐trans derivatives. Rhodopsins were prepared from bovine opsin and 18‐ and 19‐trideutero‐11‐cis‐retinal. 18‐ and 19‐trideutero‐all‐trans‐retinal were isolated as oximes after photolysis of the corresponding rhodopsins. The oximes showed the same deuterium incorporation as the starting 18‐ and 19‐trideutero‐11‐cis‐retinals and as those oximes obtained by denaturation of 18‐ and 19‐trideuterorhodopsin in the dark.These results demonstrate that during rhodopsin photolysis no detectable exchange of D or H occurs at carbon atoms 18 and 19.These facts, together with Resonance Raman data of 18‐trideutero‐bathorhodopsin and 5‐demethyl‐bathorhodopsin, establish that the primary step in rhodopsin photochemistry is not a phototautomerization involving the 5‐CH3 group. With respect to the possibility that the primary step is a phototautomerization involving the 9‐CH3 group, the situation is less clear.At this time tile experimental evidence of the various research disciplines is insufficiently conclusive to establish unambiguously which of the two possibilities, cis‐trans photoisomerization or phototautomerization involving the 9‐CH3 group, is the primary event in visual photochemistry.
Equilibrium studies on rare‐earth chelates: Interactions of rare‐earth ions with thioformohydroxamic acid
Authors: Mathur S. P. , Bhandari C. S. 
Published: September 2010

AbstractThe complexation of rare‐earth ions viz. La(III), Pr(III), Nd(III), Sm(III), Gd(III) and Y(III) with thioformohydroxamic acid has been investigated potentiometrically at 30 ± 1°C in a 70 per cent (v/v) dioxane/aqueous medium at 0.1 M ionic strength using the Bjerrum‐Calvin titration technique. Stepwise and overall stability constants of all the complex species formed are reported. The values obtained by other methods such as Least Square, Block and McIntyre, Schroder and pointwise calculation are in reasonable agreement with the Bjerrum‐Calvin half‐integral method. The stability order for 1:1 metal‐ligand chelate is found to beSm > Nd > Gd > Pr > La > Y
Synthesis of dehydroamino acids and didehydrodioxopiperazines and their conversion into α‐mercapto‐α‐amino acid derivatives
Authors: Herscheid Jacobus D. M. , Scholten Henk P. H. , Tijhuis Marian W. , Ottenheijm Harry C. J. 
Published: September 2010

AbstractA synthesis of α,β‐dehydroamino acid derivatives 12 is described, which is of possible general applicability and might be useful for the preparation of peptides which have such a moiety in their sequence. In addition, several didehydrodioxopiperazines (13–17) have been prepared. The reactivity of these compounds towards liquid H2S in the presence of ZnCl2 has been studied. Only the dehydroalanine derivatives 12a and 13 gave α‐addition products; all other dehydroamino acid derivatives and cyclic dipeptides failed to react cleanly.
Allophane and halloysite minerals. Structural considerations
Authors: de Roy G. , Verhaert I. , Vansant E. F. 
Published: September 2010

AbstractNew Zealand allophane and halloysite samples were investigated using sorption, DTA, infrared, crystallographic and Mössbauer techniques. The data support the hypotheses linking both minerals, although marked differences were detected, which are related to their structures and consequently, to their polarity.
2,2′‐Pyrromethene‐5[1H]‐one, its 1‐ and 1′‐mono‐ and 1,1′‐dimethyl homologues; Synthesis, thermal and photochemical reactivity
Authors: Onkenhout W. , van Koeveringe J. A. , Lugtenburg J. 
Published: September 2010

Abstract2,2′‐Pyrromethene‐5[1H]‐one*, together with the 1‐ and 1′‐monomethyl and 1,1′‐dimethyl homologues are prepared in high yield.2,2′‐Pyrromethene‐5[1H]‐one (1) and its 1′‐methyl homologue (2) are obtained in the Z form and the 1‐methyl (3) and 1,1′‐dimethyl homologue (4) in the E form. All four systems photoisomerize upon irradiation with light (λ > 360 nm) (Fig. 1). Separation of the photoisomeric mixtures provides the geometrical isomers that cannot be obtained via the thermal synthesis. The photoisomers do not isomerize thermally in refluxing methanol. Upon addition of sodium carbonate in methanol the photoisomers are converted back to the original isomers, demonstrating that Z‐(1), Z‐(2), E‐(3) and E‐(4) are thermodynamically more stable than E‐(1), E‐(2), Z‐(3) and Z‐(4), respectively. The presence of the 1‐methyl group in 2,2′‐pyrromethene‐5[1H]‐one systems is reflected in the thermodynamics and the photochemistry of these molecules.
Some stable substituted cycloheptatrienyl carbanions
Authors: Zwaard A. W. , Kloosterziel H. 
Published: September 2010

AbstractThe reaction of some 7‐substituted cycloheptatrienes with KNH2 in liquid ammonia is described. In several cases stable carbanions are formed. Their NMR spectra are consistent with a non‐planar pentadienyl‐like structure. A comparison of the 1H‐NMR spectra of 10 and 11 shows the paratropic character of the cycloheptatrienyl anions.
Gold clusters containing bidentate phosphine ligands. Preparation and X‐Ray structure investigation of [Au5(dppmH)3(dppm)](NO3)2 and [Au13(dppmH)6](NO3)n
Authors: van der Velden J. W. A. , Vollenbroek F. A. , Bour J. J. , Beurskens P. T. , Smits J. M. M. , Bosnian W. P. 
Published: September 2010

AbstractThe evaporation of metallic gold into an ethanolic solution of bis(diphenylphosphino)‐methane (dppmH) and NH4NO3 results in the formation of [Au5(dppmH)3(dppm)](NO3)2 with (dppm) = [Ph2PCHPPh2]−; an X‐Ray structure analysis revealed the presence of a Au‐C bond. Full physical data, including 197Au‐Mössbauer, are presented. The icosahedral Au13(dppmH)6 cation was prepared by reacting an ethanolic solution of Au2(dppmH)(NO3)2 with NaBH4; an X‐ray study is reported.
Solvent‐Reactant‐Support interactions in liquid phase hydrogenation
Authors: Koopman P. G. J. , Buurmans H. M. A. , Kieboom A. P. G. , van Bekkum H. 
Published: September 2010

AbstractThe effect of mixed solvents and catalyst support on the rate and selectivity of Ru‐catalyzed liquid phase hydrogenations has been studied. Experiments in 1‐propanol/water mixtures with Ru/C showed the adsorption of reactants on the catalyst and the reaction rate to vary with the composition of the solvent system. The influence of the support, in combination with the solvent surrounding the catalytic metal, on the selectivity in the competitive hydrogenation of cyclohexanone and cyclohexene has been studied using hydrophilic and hydrophobic supports in water/hydrocarbon mixtures. The results demonstrate the importance of both solvent‐support interactions and partition of the reactant between bulk solvent and adsorbed solvent.
Conformational energies and geometries of some oxa‐ and dioxabicyclo[3.3.1]nonanes from molecular mechanics
Authors: van Cranenburgh P. E. J. Peters , Peters J. A. , Baas J. M. A. , van de Graaf B. , de Jong G. 
Published: September 2010

AbstractEmpirical force field calculations have been performed on 2‐oxabicyclo[3.3.1]nonane, 3‐oxabicyclo[3.3.1]nonane and on 2,4‐dioxabicyclo[3.3.1]nonane and some of its methyl substituted derivatives. In 2‐oxabicyclo[3.3.1]nonane the cc and bc conformers are about equally strained. The calculations show that for 3‐oxabicyclo[3.3.1]nonane the cc, and for 2,4‐dioxabicyclo[3.3.1]nonane the bc, is the most stable conformation; the cc has a steric strain which is 8.3 kJ mol−1 higher. Replacement of the methylene units of bicyclo[3.3.1]nonane by ether oxygens seems to be mainly reflected in the amount of flattening of the wings in the various conformers. In the cc conformer of 3‐oxabicyclo[3.3.1]nonane the flattening is relatively small, whereas in 2,4‐dioxabicyclo[3.3.1]‐nonane the extent of the flattening is large with respect to the carbocyclic system. The calculated geometries and barriers to methyl rotation for the be conformer of 3,3‐dimethyl‐2,4‐dioxabicyclo‐[3.3.1]nonane and for the cb conformer of the 7,7‐dimethyl derivative show characteristic differences.
The chemistry of small ring compounds. Part 44. Solvolysis of cyclopropyl sulfides and ethers
Authors: Jorritsma R. , Steinberg H. , de Boer Th. J. 
Published: September 2010

Abstract1‐Chlorocyclopropyl methyl ether and the corresponding sulfide are methanolysed without any rupture of the three‐membered ring. The solvolysis of 1‐halocyclopropyl sulfides has been studied kinetically and takes place via an SN1 mechanism. Methyl substituents in the cyclopropyl ring promote ring opening. This, and the effect of variation of the leaving group (Cl, Br, SMe2⊕), can be rationalised in terms of relative stabilities of intermediary substituted cyclopropyl and alkyl cations.
Chiroptical properties of 2‐alkylaziridines and their N‐methyl derivatives
Authors: Maat L. , Wulkan R. W. 
Published: September 2010

AbstractSome optically active 2‐alkylaziridines and their N‐methyl derivatives have been prepared from the corresponding L‐amino acids. Both the ORD and the CD spectra of the aziridines have been determined. From these spectra it is concluded that a cis orientation of the lone pair of the nitrogen, relative to the 2‐alkyl substituent, can be correlated with a negative Cotton effect in the 200 nm region.
Rearrangement of 5α‐hydroperoxy‐6‐estren‐17‐one to 6‐oxa‐B‐homo‐4,7‐estradien‐17‐one. Preferred migration of the vinyl group
Authors: Peters J. A. M. , van Vliet N. P. , Zeelen F. J. 
Published: September 2010

AbstractCriegee rearrangement of 5α‐hydroperoxy‐6‐estren‐17‐one gave 6‐oxa‐B‐homo‐4,7‐estradien‐17‐one. This confirms that, in this rearrangement the alkenyl group has a greater migratory aptitude than the alkyl group.
The mechanism of the photooxidation of 1‐(9‐phenanthryl)‐4‐phenyl‐1‐buten‐3‐yne
Authors: van Arendonk R. J. F. M. , Laarhoven W. H. 
Published: September 2010

AbstractIrradiation of 1‐(9‐phenanthryl)‐4‐phenylbutenyne (1) in aprotic solvents containing oxygen gives two products, namely a photocyclization product, 1‐phenyltriphenylene 3, as is usually formed from diarylbutenynes, and a photooxidation product (2), derived from cyclopropapyrone. The formation of the latter product is rather specific to the butenyne 1.Both products arise from singlet‐ excited butenyne, probably via the same cycloallene intermediate 4. Supposedly, this intermediate is converted by triplet oxygen into a 1,2‐dioxetane, having an exocyclic double bond, from which the oxidation product can be formed by ring opening and further rearrangements. The negligible photooxidation of other butenynes is ascribed to the much shorter lifetime of the corresponding cyclic allenes.
4‐Nitrophenyl 4‐morpholinylphosphonochloridate: A convenient reagent for the synthesis of ribonucleoside mono‐, di‐ and tri‐phosphates
Authors: den Hartog J. A. J. , van Boom J. H. 
Published: September 2010

AbstractThe synthesis of the crystalline and easily accessible phosphorylating agent 4‐nitrophenyl 4‐morpholinylphosphonochloridate is reported. Its application to the preparation of 5′‐phosphorylated ribonucleosides (e.g. pA, ppA and pppA) as well as RNA fragments (e.g. pUpU and ppUpU) is demonstrated. Further, special attention is paid to the mild removal of the 4‐nitrophenyl group from fully protected phosphotriester intermediates.
On the relative reactivity of the C  C double bond and the [10] annulene moiety versus SO3
Authors: Lambrechts Hans J. A. , Cerfontain Hans 
Published: September 2010

AbstractSulfonation of 11‐methylene‐1,6‐methano[10]annulene (6a) with 1, 3, 4 or 6 equivalents of the dioxane‐SO3 complex in dioxane results in the formation of the 2‐sulfonic acid (6b) as the exclusive 1H NMR detectable product, whereas 1,6‐methano‐[10]annulene (5a) with 3 equiv. of this sulfonating agent already yields the 2,7‐disulfonic acid. The lower reactivity of the peripheral ring of 6a compared with that of 5a is explained in terms of a higher coplanarity of the annulene ring of 6a.
Spectral sensitization of SrTiO3 photoanodes with binuclear 1,10‐phenanthroline bis(2,2′‐bipyridine) complexes of ruthenium(II) and tris‐(2,2′‐bipyridine)ruthenium(II)
Authors: Tinnemans A. H. A. , Mackor A. 
Published: September 2010

AbstractA single crystal of strontium titanate, used as a photoanode for the photoelectrolysis of water, has been sensitized by mono‐ and binuclear ruthenium(II) complexes in acidic solution for visible light. The dependence of the photocurrent density on light intensity, dye concentration, wavelength and pH has been studied.
Chemical synthesis of thymidine 3′‐diphosphate 5′‐[(phosphonomethyl)phosphonyl phosphate]; an asymmetrically phosphorylated thymidine derivative
Authors: den Hartog J. A. J. , Lawson M. P. , de Jong E. W. P. , van Boom J. H. 
Published: September 2010

AbstractA suitably protected thymidine 3′,5′‐bis(4‐morpholinylphosphonate) derivative was converted into a derivative with two different 3′‐ and 5′‐phosphoryl functions.
Synthesis and stereochemistry of some 1,2,3,4‐tetrasubstituted pyrrolidines
Authors: Rozing G. P. , de Koning H. , Huisman H. O. 
Published: September 2010

AbstractSeveral isomeric 1,2,3‐trisubstituted 4‐hydroxypyrrolidines were obtained from reductions of 1,3‐(diethoxycarbonyl)‐2‐methyl‐4‐oxopyrrolidine and 1,2‐(diethoxycarbonyl)‐3‐methyl‐4‐oxopyrrolidine. The chemistry of these reductions is discussed. The relative configurations of the hydroxypyrrolidines were determined by chemical interconversions and spectroscopic methods, providing 1H NMR and 13C NMR data which are useful in structural assignment of other pyrrolidine derivatives.
Synthesis of six‐ and seven‐membered heterocycles by reaction of 1‐(2‐chloroethylthio)‐1‐alkynes and 1‐(3‐chloropropylthio)‐1‐alkynes with alkali metal sulfide, selenide and telluride
Authors: Sukhai R. S. , de Jong R. , Verkruijsse H. D. , Brandsma L. 
Published: September 2010

AbstractReaction of RCCSCH2CH2Cl (1, R = alkyl) compounds with dilithium disulfide (Li2S2) in ethanol gives 3‐alkyl‐5,6‐dihydro‐1,4‐dithiins (2,n= 2, X = S). With the alkali mono‐sulfide, M2S, dehydrochlorination to (vinylthio)alkynes RCCSCHCH2(3) predominates. Interaction between1,n= 2, and M2Se or M2Te (M = Li or Na) in liquid ammonia gives rise to dehydrochlorination as well as to attack on chlorine with intermediate formation of alkynethiolates RCCS−(4); if this reaction is carried out in ammonia‐free ethanol, the desired 5,6‐dihydro‐1,4‐thiaselenins and ‐thiatellurins (2,n= 2, X = Se or Te) are, in some cases, obtained. The chloro sulfides RCCS(CH2)3Cl (1, R = alkyl or phenyl) with alkali metal sulfide, selenide and telluride yield respectively 3‐alkyl‐ or 3‐aryl‐6,7‐dihydro‐5H‐1,4‐dithiepins, the corresponding 6,7‐dihydro‐5H‐1,4‐thiaselenepins and 6,7‐dihydro‐5H‐thiatellurepins (2,n= 3). When R in the starting compounds2is a Me3Si group, the unsubstituted compounds2(n= 3, R = H) are formed.